Yep, good point on the byproducts.
One device that I think sounds like a good way to improve engine life (especially for engines that get a lot of abuse or run at high loads) is the Fram bypass filters. A friend of mine swears by them.
You have the normal oil filter and everything, and the fram is a cartridge that installs elsewhere in your engine bay. It gets oil from the oil recovery system, drips it through a super fine filter (usually a roll of toilet paper, unscented I imagine) and feeds back into the oil pan. It's not "in-line" with the oil system, so there's no high pressure through it, but as the engine runs, all the oil eventually gets run through it and it scrubs it clean. In each car I've seen that has these, you can check the oil any time and it was always clear, just like a new car.
He had an interesting regime that I'm not sure I'd follow, but it was pretty fascinating. Every 3000 miles, he'd replace the toilet paper and add a quart or so of oil (however much to replace the oil that was in the toilet paper when he took it out) and that was it. He never bothered with anything else, and he drove like this for 150,000 miles as of the last time I talked to him. He has great compression, his engine runs clean, and he never has any trouble with it (it's a Volkswagen pickup, I think, the water cooled one? Haven't seen it in a couple years).
Results count, but I'd want to know more about oil chemical breakdown and whatnot before I did it, but I sure do like the idea of clean oil that doesn't abrade my engine.
I'll have to research it more by the time I'm ready to put an engine in my plane (Oh, it WILL happen, I just need to get back to work on it).
