Stay away from Jiffy Lube

[deSelys]

Originally posted by Maverick
They all use pistons, rings cylinders, valves intake and exhaust. That has remained the same for well over 75 to 100 years. Even diesels use the same internal parts. Nothing basic has changed in the design.

Maverick this is BS and you know it. Even if the basic principle is 'kind of' the same (hint: direct injection or common rail injection), the design, materials, engineering, power management,... of a modern engine have nothing in common anymore with one from 50-60 yrs ago.

Changing oil every 3000 miles surely won't hurt the engine, but it is probably an overkill... unless you plan to drive 300,000 miles with it from the start.

[beet1e]

Lazs - I'll give you 10/10 for effort on your latest answer.

But your explanation doesn't tell us why the recommended fresh oil interval has changed. Back in the 1970s, it used to be 3000 miles. Now it is much more, for both petrol and diesel engines. What has changed in the technology to achieve this?

According to you, all that's changed is that these long intervals between oil changes simply defer problems until the original owner has traded his vehicle. I call BS on that. And the reason I call BS is that new car warranties in the days of the 3000 mile oil change interval (the 1970s) were for 1 year or 12,000 miles, whichever came first. Now, with greatly extended oil change intervals, the new car warranty is typically 3 years or 60,000 miles. Cars are lasting longer, and car components are lasting longer. Read the freaking .PDF document!

How do explain that cars are lasting longer if, according to you, grit and other contaminants are allowed to circulate in the oil, which was never the case in the days of the 3000 mile oil changes, 30 years ago?

[Chairboy]

Beetle, it's true, cars are more reliable and last longer now.  But the car companies still need to sell more new cars.  Why would they tell you the procedures that will ensure that a modern car never needs to be replaced?  

I'm not suggesting that obsolescence is designed into the cars, but if you replace "excellent" maintenance with "good enough", you can sell more cars.  Nothing scheming, they're offering the same automotive lifetimes that they've always offered.  Of course, if you used the old maintenance schedules, that lifetime would be significantly longer....

[beet1e]

CB - if it's just a case of selling more cars by encouraging people to ruin their engines prematurely, then why weren't car makers recommending 18,000 mile oil change intervals back in the 1970s?

I don't buy that argument, certainly not for quality car makes. If a particular car maker produced a car which required service every 20k miles, but was knackered after 75k, it would not do their reputation any good at all, and the car buying public would go elsewhere.

[Chairboy]

Beetle, I'm saying that the cars have the same lifetime now as they did back then.  Even though the quality has improved so much, the cars will generally last the same because the maintenance intervals have increased.  If they had said "go 18k between changes" back in the 70s, then the cars would have had dramatically lowered lifespans, and that would have shown up.

Capiche?

You yourself have asserted that automotive engineering quality has gone up so much in the last 50 years, what's YOUR explanation for cars having similar lifetimes now as they did back then?

[beet1e]

Originally posted by Chairboy
Beetle, I'm saying that the cars have the same lifetime now as they did back then.  

No, I'm afraid you contradicted yourself. Because In your earlier post, you said

Beetle, it's true, cars are more reliable and last longer now.

- or maybe there's something I'm not capiching in your latest post.

[Maverick]

Originally posted by deSelys
Maverick this is BS and you know it. Even if the basic principle is 'kind of' the same (hint: direct injection or common rail injection), the design, materials, engineering, power management,... of a modern engine have nothing in common anymore with one from 50-60 yrs ago.

Changing oil every 3000 miles surely won't hurt the engine, but it is probably an overkill... unless you plan to drive 300,000 miles with it from the start.

Ok nothing in common. Lets see.

Does your automobile reciprocating engine have pistons, pistons that have piston rings to seal the cylinder?

Are those pistons contained in cylinders?

Are the pistons connected to connecting rods which then are connected to a crankshaft?

Are those cylinders contained in an engine block block? Are not those same cylinders capped by a cylinder head?

Are the cylinders provided air flow by way of intake valves?

Is the exhaust removed from the cylinder via exhaust valves?

Are the valves operated by way of a camshaft with or without valve pushrods and lifters? Are not the valves kept in place by valve guides and closed by valve springs? Is not the timing of the valve action kept correct by either gears or a chain?

Does your automobile engine not produce power by compressing then burning the fuel air mixture?

In the case of a gasoline, alcohol or combination fuel engine is not the burning of the fuel air mixture innitaited by a spark plug?

In the case of a diesel engine, is the fuel air mixture not ignited by compression?

Is the cycle of producing power not intake, compress, burn then exhaust?

Assuming you drive a 4 cycle engine does it not take 2 revolutions of the crankshaft to fully complete the above cycle?

Does the oil in your automobile still not lubricate all the moving parts, clean and at least partially cool the engine?


Please explain to me how your engine does not do these things. If they do not then I can accept your premise that there is "nothing in common" with the reciprocating internal combustion engines of 75 to 100 years ago.

[Chairboy]

Originally posted by beet1e
No, I'm afraid you contradicted yourself. Because In your earlier post, you said  - or maybe there's something I'm not capiching in your latest post.

You're right, I didn't put that clear.  Cars last longer now if you do maintenance/oil changes as often as in the old days.  I think they last the same as before if you use the manufacturer suggested guidelines.

[J_A_B]

"And... we've still not been given that as yet unspecified reason for the 3k oil changes even on the latest engines."

What is a modern engine that the manufacturer actually recommends oil changes every 3000 miles? Of the cars I've owned, the shortest recommended interval was 5K, and the last two both recommended 7500 between oil changes--and one of those was a 1990 model with an engine designed in the mid 1980's, so it wasn't exactly all that modern.  

Places like Jiffy Lube recommend every 3K miles, but they want to make money so their motivation is obvious.  Some individuals change it that often not because they necessarily "have to", but it certainly won't hurt and it gaurantees that the oil is in near-perfect condition.

If your car has a 60,000 mile warranty, you could probably never change the oil and it'd still be running after 60K miles.  It probably wouldn't reach 200K, though.  As others have said, if you don't plan on driving your car for as long as possible, frequent maintenence is likely wasted money.



J_A_B

[mora]

Originally posted by Chairboy
You're right, I didn't put that clear.  Cars last longer now if you do maintenance/oil changes as often as in the old days.  I think they last the same as before if you use the manufacturer suggested guidelines.

They last much longer now. In the 80's a typical gasoline engine lasted 200,000 miles(for a typical 1,5 liter engine). Nowdays they usually last atleast 300,000 miles. The typical oil change interval being 6000 miles back then and 17,500 miles today. Truck engines with an oil change interval up to 75,000 miles last 100,000,000 miles easily. Anyway I've never seen a properly maintained car coming to the end of it's service life because of engine wear. Other crucial parts will fail way before the engine. A couple of years ago I saw a 5 year old Volvo S70 2.4(former taxi) which had 450,000 miles on it. The engine was in perfect working order, and there was no engine related work in the service history, all services being done at the dealership I worked at. The service interval on that model was "only" 12,500 miles though.


A former teacher of mine works for a local technical magazine. He disassembles engines after 60,000 miles tests and measures all moving parts. According to his reports there's usually hardly any measurable wear in cylinders, pistons, camshafts, cranckshafts etc. after 60,000 miles. this was not the case 15 years ago. The trend has been continually downward, even when the service intervals have tripled in the last 15 years.

[Jackal1]

Yep. Especialy considering the known frequent failures of sensors/conducters/amplifiers, etc..

[lazs2]

beet... I did not say that nothing has changed.   metalurgy is more precise as is machining process.  Computer controlled fuel injection does less to wash the oil off the cylinder walls.The motors are better to begin with.   Also.. I believe that motor oils have improved.   Way back when, It was considered Ok to go 4-5K between oil changes in some circumstances.

My point is that it is probly wise to shorten the reccomended maintenance intervals if you plan on keeping the car for a very long time and...

That you can actually lengthen them on cars that you plan to get rid of in 3 or four years anyway...  let the new guy worry about it.

No matter what...  the longer you keep the same oil in the motor the more water and grit and acid in it and the less of the additives it needs will be in it.   How much it hurts is debateable.  

The sensors on your car do not analyze your oil... they figure out what type of driving conditions (as best they can) you are putting the car through and make a recomendation based on that.

lazs

[mora]

I think the "I know better" attitude expressed my Americans comes from the distrust everyone seems to have on "professionals" in the US(which seems to be well justified). It's a very sad state of affairs if you can't even trust a car mechanic, even at a dealership. Haven't they received any training or are they all ex-convicts or what? A mechanic doesn't seem to be a respectable profession in the US. What kind of education does a typical mechanic have?

[mora]

Originally posted by lazs2
The sensors on your car do not analyze your oil... they figure out what type of driving conditions (as best they can) you are putting the car through and make a recomendation based on that.

lazs

Actually they sometimes do. It's common on heavy trucks, but less so on passenger cars. I can't give an answer how they work though, because I've no idea. If there's such a sensor on Beet1e's car I don't know, I might actually call V.A.G importer tomorrow and ask if I have time.

[beet1e]

Originally posted by lazs2
The sensors on your car do not analyze your oil... they figure out what type of driving conditions (as best they can) you are putting the car through and make a recomendation based on that.

I agree the engine management system analyses factors like the number of starts, especially cold starts, but you seem convinced that the sensors do not analyse the quality of the oil. This flies in the face of what VW/Audi say themselves. But as Mora has observed ^ there seems to be a trait amongst US posters that provides a kneejerk reaction to any info that doesn't tally with what they want to believe. If VAG tells me that it's OK to run the same oil for 18000 miles because the sensors will monitor its quality, then I see no reason to disbelieve it. The American stance, however, is Reverse Dogmatism™ - the statement is adjudged to be false because it's not what you want to hear, and then the search begins to find reasons to justify that stance - in this case, it's deemed to be the car maker who "wants me to wear my engine out prematurely" so that they can "sell more cars". Well, I don't believe it, and Mora's findings reinforce my belief.