Aces High Bulletin Board
General Forums => The O' Club => Topic started by: Wolfala on March 01, 2005, 02:30:43 PM
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I was thinking...
You see Shell stations, Exxon, 76, etc...then Arco and these other stations typically 15-20 cents less then those.
My question is - WHAT IS THE DIFFERENCE between the big brands and whatever these guys carry? Has anyone done a test to see if engines will perform any differently over the life of the car with gas purchased at the places that are not big name?
Wolf
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I've never noticed a difference in mileage or performance in my POS.
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none, zero, nada, zilch in fact they are distributed across the nation in the same pipeline coming from the same refineries. any "special additives" to make them brand specific are added to the fuels as they are pumped into the tanker trucks.
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Also note that putting a higher octane fuel in your car will do nothing for performance or reliability unless it requires it. Way to many folks put high test in a low compression engine thinking it will do some good.
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They each add a proprietary additive package. Some are sophisticated and some are rather basic. I was never particularly sold on the value of these but some of the data can be impressive as far as cleaning deposits and keeping them off. The net result should be more power, more efficiency and more longevity with the better packages. The right gasoline can even make it easier for an automaker meet 100,000-mile emission testing standards.
I went to a media event at the Chevron Texaco campus last summer and met with their fuel engineers and North American V.P marketing celebrating their TOP TIER Gasoline rating (when they were about the first to earn it). This goes beyond EPA requirements and was developed by BMW, General Motors, Honda and Toyota as a “recommended” gasoline criteria for longevity and emissions, etc. I don’t go out of my way to buy branded gasoline, but I did get a bottle of Techron additive soon afterwards :) FWIW, this is not a formal promotion of ChevronTexaco, but they do make an effort to be a leader in this category and they showed a real interesting before and after display using engine valves. According to their information a few tank fulls can clean away a lot of deposits. It seems the other majors are embracing “quality” gasoline again as well. Again, interesting but like many price tends to be king for me.
Charon
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I wish that were the case here in kalifornia. We have our own state EPA setting standards for fuel and emissions. Our gasoline cost is higher. We still have MTBE in our gas and we get it from one pipeline coming up from Texas. The MTBE is a refinery added compound which makes our gas cost higher. Gov. Davis signed a bill eliminating the requirment, but we still have binding contracts for some time. Turns out the California EPA sciencenuts didn't do their homework on how toxic MTBE is. They were all atwitter on it being some kind of a way to recycle old oil in a freindly manner. We are stuck with it in our ground water now.
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of course theres a difference but you wont feel it driving around town. Im not sure about engine life but it does affect fuel milage. Also I noticed some gasoline brands provide more power on my bike. In situations like that its more obvious which brand is better but this is just my opinion,
so Id say the most noticable difference would be in mileage. I've noticed some brand get better milage but it all depends on which region you live and elevation and its always changing anyways. One brand might be great during this summer then suck next summer etc...
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other than octane the only difference is the additives they each put in their gas, in some cases the plain gas is delivered
in bulk to a common distribution
point and when the tanker trucks come in to be filled, the additives are added fore each brand.
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I'm very familiar with MTBE bustr. IMO the ultimate blame for the additive falls with the ethanol lobby (and to some extent the MTBE lobby) that pushed for an oxygenate mandate in the Clean Air Act instead of setting a an emissions standard and letting the industry figure out how to meet it. The two oxygenates used to meet this forced requirement are ethanol and MTBE (which was much easier to use, and frankly, more profitable for the oil/petrochemical industry).
MTBE, and in some areas ethanol, are used as octane enhancers and in higher concentrations to make "reformulated gasolines" in EPA air quality non-attainment areas. A little MTBE can go an awful long way where unpleasant flavor is concerned, though the jury is still out on the health issues.
Charon
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When I go buy gas two things matter to me. 1st how much the gas cost me. 2nd how much the cigeretes cost me. Has nothing to do with btu etc...
unless Im buying gas for my bike. then I only go to two different gas stations. Sometimes I have to I get gas elsewhere but if it sucks I run mytank near emtpy before I go to my prefered gas stations again.
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As it was said earlier the difference is in the additives. Some additives don't lubricate the valves as good as others, and some don't clean up carbon deposits as good as others. If you are conserned, it might be good idea to fill up at a name brand station once in a while.
Doesn't any magazines do tests on different fuels over there? There has been a couple of test done here by running similar engines for a long time on different fuels and then cracking them open. Nowdays the differences are not that great, but 10 years ago the differences were huge. One particular brand even caused valves to stick open in certain engines.
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Charon,
I did a little research on MTBE a few years ago and the main concern was with MTBE percolating down to the water table. The effects, thereafter were the main concern. I agree with you that as an oxygenate, it is far superior to ethanol and does less harm to the engine in the long haul - however since the jury is still out on the carcogenic nature of MTBE - the benifits did not justify the political fallout of keeping it in the pipe.
Wolf
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I did a little research on MTBE a few years ago and the main concern was with MTBE percolating down to the water table. The effects, thereafter were the main concern. I agree with you that as an oxygenate, it is far superior to ethanol and does less harm to the engine in the long haul - however since the jury is still out on the carcogenic nature of MTBE - the benifits did not justify the political fallout of keeping it in the pipe.
Absolutely. No one wants chemical flavored water anyway, even if it won't kill you :) It's amazing how little MTBE can go a long way in the water table. Even a car accident can raise concerns in an area where people rely on well water.
[edit: One notable issue short term with banning or replacement is making up the shortfall. The amount used as an oxygenate in required areas or as an octane booster may not be significant in general, but when you consider that we operate at 98 percent of refining capacity during peak periods it is significant enough to be a major problem.]
Charon
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Originally posted by bustr
I wish that were the case here in kalifornia. We have our own state EPA setting standards for fuel and emissions. Our gasoline cost is higher. We still have MTBE in our gas and we get it from one pipeline coming up from Texas. The MTBE is a refinery added compound which makes our gas cost higher. Gov. Davis signed a bill eliminating the requirment, but we still have binding contracts for some time. Turns out the California EPA sciencenuts didn't do their homework on how toxic MTBE is. They were all atwitter on it being some kind of a way to recycle old oil in a freindly manner. We are stuck with it in our ground water now.
I thought by now everyone had banned MTBE?
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Originally posted by Charon
I'm very familiar with MTBE bustr. IMO the ultimate blame for the additive falls with the ethanol lobby (and to some extent the MTBE lobby) that pushed for an oxygenate mandate in the Clean Air Act instead of setting a an emissions standard and letting the industry figure out how to meet it. The two oxygenates used to meet this forced requirement are ethanol and MTBE (which was much easier to use, and frankly, more profitable for the oil/petrochemical industry).
MTBE, and in some areas ethanol, are used as octane enhancers and in higher concentrations to make "reformulated gasolines" in EPA air quality non-attainment areas. A little MTBE can go an awful long way where unpleasant flavor is concerned, though the jury is still out on the health issues.
Charon
Charon I don't see how you can rightly blame the ethanol lobby for the MTBE disaster, since they were pushing the alternative to MTBE. It sounds like their lobbying backfired.
As far as health issues of MTBE contamination, honestly guys, what does your common sense tell you about drinking water that smells like turpentine?
In all seriousness, do you consider the jury still out on whether cigarettes cause lung disease?
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Originally posted by oboe
In all seriousness, do you consider the jury still out on whether cigarettes cause lung disease?
Ahem... I think the warnings are printed right on the pack. :)
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Personally, I like to keep my car fueled with 100LL down at ye' old airport. Yessir, fastest Buick Regal on this side of the second level parking lot at my office!
mebbe not. I used to occasionally buy 100LL to run in my motorcycle, other then that, the only engine I use that uses it is made by Lycoming.
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Wolf - Charon & Mora have already said it - Additives.
I have a diesel car, and the additives are even more critical in diesel. You might not notice any difference when driving along smoothly, but those additives could make a difference by avoiding trouble like having your fuel wax due to cold weather, or having problems with clogged injectors.
When I first switched to diesel about 1˝ years ago, I asked a diesel driving friend if I should use any third party additives. He said no, but warned me against being tempted by supermarket fuel which retails much more cheaply than at ordinary filling stations. That's because supermarket fuel is cheap for a reason - the additives might be missing.
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Charon,
Years ago I worked at a Saturn dealership. It seemed they were very adamant about after every service, they'd toss in a bottle of Techron. Apparently it made a hugr difference with valves, mileage, etc.
Since then, I've always put a bottle in once a month. Seems to keep the mileage on the up n up.
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Charon I don't see how you can rightly blame the ethanol lobby for the MTBE disaster, since they were pushing the alternative to MTBE. It sounds like their lobbying backfired.
They were very successful. First off they got an oxygenate mandate as a required solution written into the CAA. The oil industry (except for a few companies with notable MTBE interests) fought this and only asked that the EPA set a performance measure and let the industry provide formulations that meet it. The oil industry lost. There was plenty of ethanol added to gasoline as a result to meet that requirement (in addition to MTBE), particularly around the corn belt. Not the full win they would have liked, but good enough. You kiss 52 cents out of your highway funds for each gallon of ethanol added to gasoline BTW to make it "cost effective," a big subsidy that keeps ADM and the like happy. Your and my tax dollars at work.
They haven't stopped though, and the latest versions of current energy policy have all contained a huge ethanol mandate. They have largely given up on the oxygenate/clean air benefits angle though (since that has been scientifically determined to be a wash in most cases, useful in some wintertime CO requirements and a negative in other “summertime” cases). It is now the "reduce dependence on foreign oil" angle that is pushed. But again, it’s just agribusiness and Washington politics as usual if you look long and hard at the costs and results.
Charon
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lepaul, i worked in car dealerships for 40 years, the dealer and the techs get a kick back on every bottle of 3rd party additive they "sell", not to say it will do harm, but not to say it will help.
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Yeah Le Paul, I'm somewhat of a believer now myself. They put on a good dog and pony show to make me one, but third parties in the auto industry seem to support that too and they have no incentive to unless there's a pay off.
The results on the before and after valve stems were fairly significant. I was told one treatment would generate the "after" but I still find that somewhat hard to believe.
[edit: Ah John, that's interesting. I do know they use a certain brand of gasoline when conducting that 100,000 mile emissions testing. I wonder if there isn't something else at work there too :)]
Charon
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All I know is some gas burns better than others. Not kidding ya on this one.
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Originally posted by Chairboy
Personally, I like to keep my car fueled with 100LL down at ye' old airport. Yessir, fastest Buick Regal on this side of the second level parking lot at my office!
mebbe not. I used to occasionally buy 100LL to run in my motorcycle, other then that, the only engine I use that uses it is made by Lycoming.
Can always tell a guy running a regular car on 100LL, he's the
one with the lovely light gray lead deposits coating the inside of
his tailpipe :)
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Hey I got an great idea I'm gona run 100LL in my bike.
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true story, met a hillbilly once who ran his farm truck on half gas and half diesel, he said "it runs good , but smokes a little" i asked why he did that, he said,"my brother in law works for the county".
explanation, he got the diesel for free.
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Originally posted by rabbidrabbit
Also note that putting a higher octane fuel in your car will do nothing for performance or reliability unless it requires it. Way to many folks put high test in a low compression engine thinking it will do some good.
Actually, most modern cars will benefit in terms of power and mileage from using the higher octane fuels, especially when ambient temperatures are relatively high.
The engine management systems we have now use what manufacturers refer to as "adaptive strategy" to optimize performance in real time. In particular, much of the time ignition timing can be stretched out a tad farther without causing detonation when using higher octane fuel, and this allows the management system to take advantage of that to achieve better efficiency.
Car manufacturers aren't going to publicize that because in addition to certifications for emissions and fuel mileage, they also advertise cost per mile figures. But if you're in the loop, factory service representatives will all tell you that their cars run better on premium fuel, and I observed that to be true based on the preponderance of anecdotal information I saw during my career in vehicle repair. 1 to 2 miles per gallon better during highway cruise on 92 octane compared to 87 octane is pretty common.
Aside from that, the other things being said here regarding additives are correct. I've seen many studies that documented enhanced engine internal cleanliness as a result of additves.
This both increases engine life for the obvious reason, and also ensures optimal performance. Calibrations in the management systems are dependent upon fixed sizes in combustion chambers (which are thrown out of whack by deposit buildup) fixed volume delivery and spray pattern from injection nozzles (which are thrown out of whack by deposit buildup) and consistent control of compression and blow-by (which are thrown out of whack by deposit buildup). Power, mileage, and emissions are all affected by all this significantly.
Deposit buildup on the backs of the intake valves in particular is a huge factor. Fuel additives that minimize this buildup prevent an odd phenomenon - the buildups are porous and actually soak up some of the fuel being delivered from the injection nozzles. This creates artificially lean mixtures in comparison to what the management system expects from the table-based fuel delivery, causing the system to have to make "off-center" compensations and almost always resulting in inconsistent performance (such as throttle lag and reduced power/mileage).
Deposit buildup in injector nozzles is also a frequent cause of hard starting, both because of the obvious (wrong volume delivery and spray pattern) and because deposits can cause nozzle leakage - the system should maintain a minimum "rest pressure" so fuel delivery begins instantly when the engine is cranked, but leakage reduces that to zero which means there's a lag as the fuel pump pressurizes the delivery circuit.
There are really significant differences in the additive packages of the various brands. I can't say which fuel is best now, but while I was in the business and privy to current information, Chevron and Shell were always really good. I particularly like the Chevron Techron over-the-counter additives. Also, major brands tend to have higher standards regarding storage facilities and filtration systems, resulting in better physical cleanliness of their fuel.
Bottom line, you get what you pay for, and smart shoppers do better (as is the case with many things ;))
culero (ASE certified Master Technician with 25+ years experience, hung up the wrenches in 2001)
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Charon,
When I worked at Saturn, it was 1996. The engines in those cars were known to not be the greatest, but they did give those plastic cars great mileage. One thing about Saturns Ive been told (again, third party) was the valving. Techron certainly kept them clean. I know my 95 Saturn SC2 had a noisy timing chain and the mechanic made mention of how clean the engine was.
I just make it part of the regular maintenance. Some stores have it cheaper than others. Ive noticed its pricier at auto stores versus, say, the local Target, etc.
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Originally posted by Charon
FWIW, this is not a formal promotion of ChevronTexaco, but they do make an effort to be a leader in this category and they showed a real interesting before and after display using engine valves.
Charon
When I lived in north AL there was a Smile(i think) station in the middle of town that was consistently 15-20 cents cheaper than the Chevron on the edge of town. And all the other stations really.
I asked the attendent about it. He told me the fuel truck would leave Chevron and come straight to his station to fill his tanks. Same gas he said. I was skeptical, but my old truck seemed to run the same on gas from either station.
A couple of weeks later I happened to see the fuel truck pull out of the Chevron. I followed it and watched it pull right into my little discount station.
My question is, do the trucks carry different fuels for different stations at the same time?
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Originally posted by Lazerus
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My question is, do the trucks carry different fuels for different stations at the same time?
They can. The typical tanker has more than one compartment.
This is a distribution system thing. A wholesaler may need to consolidate delivery vehicles to deliver to different customers in smaller markets.
Its also true that the same truck may deliver Michelin tires and ElCrappoDeluxe tires. They're still not the same ;)
culero
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As culero said, they can carry multiple products in multiple compartments. Technically, if you're branded you have a branded supply contract and cannot shop around. You are guaranteed supply from the major oil company, but you have to take whatever price is offered (usually 6 cents or so higher than the spot market).
If you are an unbranded marketer, you can look for the lowest wholesale price at the rack and order as needed for the stations in your operation (but in a crunch you may find yourself unable to get supply or paying higher than branded for that supply). You can also have a “branded like” supply arrangement with a wholesaler for unbranded product at a certain price point above the market. You can even, though not typically, buy branded surplus even with branded additives. And, the same truck could fill up at the same terminal with branded gasoline (with the appropriate additive package) and unbranded gasoline in different compartments. The big no no is buying unbranded supply when you are a branded dealer or marketer. But the oil companies track that pretty closely to make sure it doesn't happen.
Typical margin on a gallon of retail gasoline for the retailer is under 10 cents. In some markets it approaches zero, especially when you add in the credit card processing fees and hypermarket competitors that don’t really aim to make money on the gasoline product and use it as a loss leader or loyalty reward for store purchases. The focus of the “traditional” retailers/marketers today is to use gasoline as a volume generator and make money in the store, the deli, the ATM and the car wash. If it’s a good month for gasoline then all the better. If it's a bad month (where you can end up losing a few cents pre gallon for a period of time) then you better have all your other profit center ducks in a row.
Charon
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Originally posted by culero
Actually, most modern cars will benefit in terms of power and mileage from using the higher octane fuels, especially when ambient temperatures are relatively high.
The engine management systems we have now use what manufacturers refer to as "adaptive strategy" to optimize performance in real time. In particular, much of the time ignition timing can be stretched out a tad farther without causing detonation when using higher octane fuel, and this allows the management system to take advantage of that to achieve better efficiency.
..........(ASE certified Master Technician with 25+ years experience, hung up the wrenches in 2001)
That's true but the adaption doesn't necessarily happen automatically. Many makes reguire an adaptive drive to be made by a tech by a standard procedure. Others adapt automatically, but that happens over time, and the driver will not notice an instant change if they fill up with a higher octane fuel.
EDIT: Now that I gave it a second thought, most makes reguire an adaptive drive to be made to ensure that the car runs smoothly when it's returned to the customer. I believe most makes will actually adapt automatically over time when driven normally.
Just out of curiosity. What kind of schooling is reguired to be a certified technician there?
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Culero - very interesting post at 2:11. :aok
Originally posted by culero
Deposit buildup on the backs of the intake valves in particular is a huge factor.
Back in the 1970s, I had a car with a 2.3 litre engine with a blown head gasket. The oil had a milky appearance - I understood this to be because of antifreeze having leaked into the oil.
So a friend helped me to dismantle the engine. We took off the cylinder head and removed all the valves. The exhaust valves had burned reasonable clean, but the inlet valves - wow! :eek: The deposits were so bad that the valves looked more like bells than valves. My good friend volunteered to clean them up while I went to buy some new valve springs. When I got back, he had finished. He'd had to use a knife to break off the deposits, which were rock hard. I swept all the debris into a shovel and put it in a dustbin. I was amazed how much there was. And the old valve springs were so worn that they had compressed to about half the length of the new ones!
That was a carburated engine. I do believe that carburettors were set to deliver the correct stoichemical combustion mixture at normal running speed, but this led to the engine running richer than optimum at low speeds - hence soot deposits in the exhaust pipe if the car had been bumbling around town for a few weeks. I take it that with modern computerised engine management systems, the ideal combustion mixture can be maintained under any conditions.
Lazuerus, the other guys beat me to it - a tanker can have about seven compartments. I found that out when working for Phillips Petroleum in the 1980s, designing a sales order system. The other thing I found out is that various fuel retailers will uplift product from other companies when it suits them! Eg., a tanker from company ABC has run low on a product, but needs to make a delivery in an area far from home base. Rather than drive all the way back to home base, he will uplift fuel from company XYZ in the area where delivery is to be made and then make the delivery. ABC and XYZ will have a reciprocal arrangement for doing this.
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mtbe is just more EPA junk science.. we should put a stake through the heart of the EPA while we still can.. in just a few more years the EPA will permeate every facet of our daily lives. For the worse...
If you thought the IRS and the DMV were evil.... you haven't seen anything yet.
lazs
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Originally posted by mora
That's true but the adaption doesn't necessarily happen automatically. Many makes reguire an adaptive drive to be made by a tech by a standard procedure. Others adapt automatically, but that happens over time, and the driver will not notice an instant change if they fill up with a higher octane fuel.
EDIT: Now that I gave it a second thought, most makes reguire an adaptive drive to be made to ensure that the car runs smoothly when it's returned to the customer. I believe most makes will actually adapt automatically over time when driven normally.
Just out of curiosity. What kind of schooling is reguired to be a certified technician there?
No schooling is required, although many schools here exist that target ASE certification as their baseline for curriculum. Demonstration of knowledge by testing and accumulation of on the job experience (minimum 2 years) are how you become certified.
Various areas of specialty are tested for certification - engine repair, engine performance (management systems), transmission, drive train and suspension, electrical systems, heating/air conditioning, and brakes are the eight seperate certifications you need to be rated Master.
Recertification every 4 years is required to maintain status. ASE contracts with local universities nationwide to conduct their testing, and pays their faculties to set up controlled test environments and proctor the tests. The cost to the technician is about $70 per test.
ASE also certifies medium and heavy duty truck technicians, in similar areas, and also paint/body repair technicians. ASE is a non-profit industry-based organization that's been around since the late 70s.
I've always participated and supported them enthusiastically, because they test rigorously (you need to know or you won't pass their tests) and have worked hard to maintain an independent status - no government association. They've become so well respected they are our national standard for technician certification. Its IMO a model for how other trades can keep the government out of the business of regulating them.
As to adaptive strategy - I realize what I wrote was very general. It is pretty much specifically correct for the Big 3 US manufacturers. And what I specifically referred to (timing changes in high ambient temperature in reaction to fuel grade) will actually happen pretty quickly. In closed loop operation, the ECU will creep the time out until feedback from the knock sensor tells it to stop and/or cut back. That obviously will happen a little bit later with more octane, resulting in just a tad hotter timing and thus a tad better performance.
Yes, it does take a little longer for this to be fully integrated with adjustments to the fuel delivery curve, because the ECU checks overall performance for fixed periods of time before changing "blocks" (imagine a checkerboard, witrh each square representing a slightly different table for management parameters) in order to make more extensive adjustments such as overall curve, etc.
Of course, some of the smaller and cheaper cars' systems aren't as complex, but in general the above is pretty much accurate.
culero
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Originally posted by Charon
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The results on the before and after valve stems were fairly significant. I was told one treatment would generate the "after" but I still find that somewhat hard to believe.
I've done enough engine surgery in my time to be able to tell you its absolutely true.
Ask Capt. Virgil Hilts, he's more expert than I am in this particular area (engine repair).
culero (more of a "GP", likes heating/AC/electrical best)
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Originally posted by beet1e
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That was a carburated engine. I do believe that carburettors were set to deliver the correct stoichemical combustion mixture at normal running speed, but this led to the engine running richer than optimum at low speeds - hence soot deposits in the exhaust pipe if the car had been bumbling around town for a few weeks. I take it that with modern computerised engine management systems, the ideal combustion mixture can be maintained under any conditions.
Yes. Its actually been demonstrated in urban areas that a modern management system can produce exhaust with less pollutants in it that the ambient atmosphere its breathing. (Ironic, eh? :))
The fact that many carburetted engines produced more soot at low/idle speeds wasn't that the calibrations for normal speed required that low speeds be too rich. Actually, you're talking about seperate control circuits within the carburetor.
The low speed circuits have a tougher job inherently because they have less air to work with due to the throttle being closed. The calibration of the low speed circuits is much more sensitive, and thus often gets out of whack. Plus, other conditions which tend to exaggerate mixture problems (such as float level problems, leaky fuel inlet valves, manifold vacuum leaks, etc) can have a more profound effect at low engine speeds.
Actually, properly maintained modern carburetors on healthy engines became pretty good before fuel "injection" (its actually not injection, but that's another discussion ;)) took over. What made them dinosaurs is the basic fact they were tricky mechanical beasts to keep in proper tune, while injection systems were MUCH less complicated mechanically and relied on electronics to maintain calibration (MUCH MUCH more reliable).
culero
edit PS - thats "stoichometric", BTW :cool:
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Culero and folks, great thread! It would be great to see some non partisan test results on which additives are how effective.
Culero, I agree completely with your point on higher octane yeilding slightly better results. In higher compression cars like my Prelude (10:1) I can see even as much as 4 MPG increase when using 93 Octane vs 87 Octane fuels. However, for the 4-5% better milage you pay 20-30% more in fuel costs. Hence, a net increase in operating costs. For that reason I said it serves no benefit for those with low compression engines and marginal benefit even for those with high compression engines like mine which "require" 92 Octane.
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Originally posted by culero
edit PS - thats "stoichometric", BTW :cool:
Yes, stoichiometric, even. :) I don't know where I got stoichemical from. :confused:
OK, Culero, here's a question for you: Would you recommend the use of 3rd party fuel additives for my diesel car? The temperature here rarely drops below -5°C, and the maker (VW) doesn't make any recommendations for additives. Another question - what is your opinion of those "premium" fuels, which claim to clean the parts of your engine that other fuels cannot reach, but which cost MUCH more? On fuel and oil, I have taken the view that if such products were needed, VW would have told me.
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Originally posted by rabbidrabbit
Culero and folks, great thread! It would be great to see some non partisan test results on which additives are how effective.
Culero, I agree completely with your point on higher octane yeilding slightly better results. In higher compression cars like my Prelude (10:1) I can see even as much as 4 MPG increase when using 93 Octane vs 87 Octane fuels. However, for the 4-5% better milage you pay 20-30% more in fuel costs. Hence, a net increase in operating costs. For that reason I said it serves no benefit for those with low compression engines and marginal benefit even for those with high compression engines like mine which "require" 92 Octane.
Depends on what you mean by "benefit". You are right in terms of short-to-medium-term cost/benefit.
Personally, I like visting the pumps less (thus using less ragh....err, Arab petroleum) enough to be willing to pay a slight premium.
Side note: that's a BIG reason why I am still driving my POS 1985 Ford Tempo diesel - it gives me 30+mpg in-city, about 40 highway. Plus, I appreciate the ease of maintenance and superior low speed performance attributes a diesel provides, but that's another discussion.
Also, while I cannot positively confirm it, anecdotal experience makes me tend to believe that the premium fuels run cleaner. I surmise they may get extra additives, but that's just a guess. That contributes to long-term cost/benefit, if you tend to drive vehicles long enough to realize that.
Hell, I even run my boat and lawnmower on premium (and they are carburetted) because of this belief.
culero (believes his beliefs in this area are "informed" ;))
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Originally posted by beet1e
Yes, stoichiometric, even. :) I don't know where I got stoichemical from. :confused:
OK, Culero, here's a question for you: Would you recommend the use of 3rd party fuel additives for my diesel car? The temperature here rarely drops below -5°C, and the maker (VW) doesn't make any recommendations for additives. Another question - what is your opinion of those "premium" fuels, which claim to clean the parts of your engine that other fuels cannot reach, but which cost MUCH more? On fuel and oil, I have taken the view that if such products were needed, VW would have told me.
As I mentioned upthread, keep in mind VW advertises as part its products attributes "cost per mile". Think about what that implies. They aren't talking about cost over the long run. Go deeper than what the corporate line is, ask someone who has personal contact with a factory service engineer and you may hear differently ;)
My experience in the trucking side of things was only about 4-5 years, the bulk (and most recent) was in automotive (gasoline) so I'm less informed as to diesel (we have very few diesel cars here).
That said, my experience is that anecdotal information is all over the map regarding 3rd party diesel additives, and what I've heard specifcally from OEM factory reps is that all you need is to buy top-quality major brand fuel (that's what I do in my car). ]
If you do wish to use additives, some knowledgable folks I know who DO recommend them recommend POWER SERVICE (http://www.powerservice.com/) and LUCAS (http://www.lucasoil.com/) products.
FWIW, I am a BIG fan of the Lucas oil treatments, they are excellent.
culero
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If you are running higher test fuel solely for the benefit of a cleaner engine would it not be signiificantly more wise to run on the cheaper fuel and toss in a cleaning additive every 15k miles or so? This would give you the benefits at a fraction of the costs.. The other benefit you mention, 1-5% better mileage over the range given by a small fuel tank should be rather insignificant. You are talking maybe a quart over the capacity of 15 gallons. I don't know about you but that amount makes no difference to me when deciding when to refuel.
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Originally posted by rabbidrabbit
If you are running higher test fuel solely for the benefit of a cleaner engine would it not be signiificantly more wise to run on the cheaper fuel and toss in a cleaning additive every 15k miles or so? This would give you the benefits at a fraction of the costs..
If in fact the additives are the ONLY factor involved in greater cleanliness, yes. Points to consider:
1) How effective is it to use what you know will dirty things up more, then clean occasionally, compared to running the cleanest possibility all the time?
2) Further, how often and how much is enough if you choose to add cleaners intermittently?
3) If better power performance is the result of higher octane fuel, doesn't it follow that for the same level of power produced, less throttle input (therefore less burn) is required? Wouldn't that automatically result in less deposits from the combustion process?
Those are necessary question to answer if you wish to compare costs accurately.
Originally posted by rabbidrabbit
The other benefit you mention, 1-5% better mileage over the range given by a small fuel tank should be rather insignificant. You are talking maybe a quart over the capacity of 15 gallons. I don't know about you but that amount makes no difference to me when deciding when to refuel.
Don't get me wrong, I agree you are making very valid points here that represent very good advice for many (arguably most) people.
What I am challenging and discussing with is your original assertion that there are NO benefits :)
culero
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You challanged them properly. I was generalizing my position since I'm yet to believe that the costs outweigh the benefits in most if not all circumstances. You make valid points but I'm yet to be convinced that my simplified response is inaccurate in whole. So far I don't see how the costs outweigh the benefits.
I'd love to see some sort of unbiased study of say Techron and other additives that would help explain their real benefits if any. I'd have no problem with dumping something in my tank if I had reason to believe it was superior to what I'm doing now.
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Originally posted by rabbidrabbit
snip
You challanged them properly. I was generalizing my position since I'm yet to believe that the costs outweigh the benefits in most if not all circumstances. You make valid points but I'm yet to be convinced that my simplified response is inaccurate in whole. So far I don't see how the costs outweigh the benefits.
We have no argument here, I agree you're right regarding cost/benefit in general for many/most people.
I'm simply arguing that there usually is some notable immediate performance advantage, that there may be long-term cost benefit for those who use a car all the way up due to less engine wear, and also the intangible benefit that better mileage is worth paying a tad more for (in my case anyway, as always YMMV ;))
I think we're basically on the same page, we're just developing different preferences due to personal taste.
culero
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Hell I use 92+ in my car all the time and I notice a difference between 87 and the higher octane ratings. I started biting the bullet and buying the premium because Chrysler desgned these engines really wierd. You run them on 87 and they run all right but the PCM pulls timing and you lose HP and MPG all across the board. Been using 92+ for some time now and the car gets amazing milage (comapred to 87 at least) and runs a bit better and a bit cleaner.
But, that's just my car...it may not be the same for everyone.
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Supply and Demand. The bigger places have a lot more supply and can make more of a profit by even selling it less.
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Tex,
From what I understand, you will notice a more significant benefit as your compression ratio increases. If your car runs 10:1 or better you might notice some significant benefits but from my experiements the benefits don't outweigh the additional cost from a monetary perspective. On a higher than 10:1 compression ratio it may well turn out to make economic sense. How about doing some mileage tests with 87 then 92 octane fuel? Best to quantify your costs.
According to motortrend
http://www.motortrend.com/features/care/112_0306_cc/index.html
"· Fuel-injector cleaners, such as Chevron's Techron, clean injectors almost as well as professional-grade products. Clean injectors alone can account for up to five-percent-better fuel economy.
· Don't waste money on a higher-octane level of fuel than is recommended in the owner's manual. Under most conditions, you get nothing in return."
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Motor's not quite stock anymore. I've not run compression tests on it but I'm getting about 5 MPG or so more with 92+ than I was with 87. I tested it with all octanes plus the difference between an ATX and a MTX transmission. Results are like night and day. But, as I said, that's for my car and it's not the topic of the dicussion.
On that note, I have noticed better overall quality from Chevron's gas.
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That's a good point, Texace.
Ive got an '04 Dodge Stratus, 2.7L V6. 20k for miles. I commute about 55 miles total, every day. I think I'll try 92 oct for 2 weeks, along with the usual bottle of Techron every month and see if I notice any real difference in mileage
The biggest hit to my mileage this time of year is letting it warm up (Im in Maine). Idling for 13-14 mins aint helping...but it beats sitting in a frozen car!
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There's something wrong with the fuel and the oils over there if you need to use additives. You guys do use synthetic oils, right?
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Originally posted by mora
There's something wrong with the fuel and the oils over there if you need to use additives. You guys do use synthetic oils, right?
I take it you mean 3rd party additives - the stuff in small bottles you add yourself? If so, I agree with you. My car maker (VW) makes no recommendation to use such additives. I use a high performance oil designed for diesel engines, and buy it right from the VW dealer so that I know I'm getting the right thing. There probably is a slightly cheaper alternative, but I've only had to add 1 litre in 28,000 miles (45.000km.) so I don't worry about the cost. And I just use the standard diesel - no premium rate gimmicks.
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Regarding oils... I've heard that most people still use mineral oils in the US because it's so cheap over there, like $2/gal. When synthetic is 5 times more expensive people don't use it, even when it can be used for 2 to 3 times longer. In rest of the world no manufacturers haven't even allowed the use of mineral oils for the past 5 years at least.
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There is a difference in octane ratings.
If I huff regular all I get is a headache, and if I huff premium I see colors and get dizzy and fall down.
I use Premium only.
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When you drive behind someone burning cheap gas, you will know
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My car needs 91 or better to run at full boost, and if the fuel is less than that, the ECU detects impending detonation and reduces boost and retards spark timing. It's very obvious when this is happening, because you can feel the loss of power. In effect I have a pretty decent octane measuring device and I can tell you that Costco and Safeway and a few local mom and pop bargain stations are selling fuel that is no up to spec.
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Originally posted by mora
There's something wrong with the fuel and the oils over there if you need to use additives. You guys do use synthetic oils, right?
Nothing but synthetic in my cars.