Quote:
Originally Posted by Phantom
Some of the older engines such as Flat Tappet cam engines need special oil or a ZDDP additive (I believe ZDDP is zink and phosphorus).
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You are correct. Older engines (pre 90s mostly) need the zinc and phosphorus additives because those substances are no longer put into todays oil.
To answer the OP (and agreeing with most everyone in this thread) I would never put Slick 50 in my oil. Here's the scientific why: Slick 50 is Teflon (PTFE, whatever) and the problem is twofold- the small portion that makes it through your oil filter, after clogging it up of course, bonds and coats to metal surfaces which reduces the clearances of everything that it touches which in turn increases engine wear and blocks oil passages. The second thing that it does is harden. This happens at higher temperatures and turns the liquid teflon into solid flakes, which in turn block your oil passages more and on top of that teflon is EXTREMELY hard, harder than metal, so it starts to scratch your cylinder walls, piston rings, and your entire valvetrain. The second part doesn't necessarily happen with your granny driver, but under normal driving conditions, those with lean burn engines, and the ones who have grill blocks which increase the heat in the engine, the hardining will happen eventually. So you have just paid 20 extra dollars per oil change to ruin your engine.
The best modification you can do with your oil is to switch to full synthetic. Full synthetic is more slippery at a specified viscosity which decreases wear on the engine, it does not break down nearly as fast as conventional (thus longer change intervals), and in engines with 100k miles on them, it softens dried out/brittle seals and swells them, which will cure a small amount of burning oil/ oil leakage if you have any. This is why you cannot switch back to conventional after putting in synthetic, the seals will start to dry back out again and shrink, thus causing oil leaks.
Two things about synthetic: Make sure you use FULL synthetic. All conventional oils are a synthetic blend of some sort, usually between 25% and 75% synthetic. Don't buy into marketing. The cheapest full synthetic is better than the best conventional (excluding CenPeCo and AMSoil conventional blends). Mobil 1 has a lot of hype and it isn't the best, but it still is good. Also, make sure you use a good filter that is meant for synthetic, with the longer oil change intervals you will want a good filter.