The whole deal on oil? (stupid question inside)
 

Ok, I know this is a dumb question and I'm not a mechanic nor am I foreign to the automotive scene, but one of the stupid things I never figured out was about oil types. Simply put, could someone please tell me what the difference between regular old oil and partial-synthetic and full synthetic is? I never really thought about it till lately. I noticed the full synthetic stuff is a lot more expensive so I figured that this must be the best kind of stuff, but I wasn't sure. I have an '86 300E and I don't like to skimp on maintainence stuff, I try to buy the best (and most expensive) stuff for it. Can someone key me in here, should I be buying stuff like full synthetic Amsoil and Redline or should does it matter if I buy regular Penzoil or whatever?

I'll throw in my 2 cents.

Your car was made 16 yrs. ago. How widely available, widely used was any form of synthetic in 1986?

I won't argue that synthetic MIGHT be better for newer cars. It's my belief that in older cars, you're wasting your money and that you stand a good chance of creating leaks that weren't there before. Don't ask me how I know this.

Use a Mahle/Knecht, Hengst; Mann filter and a quality conventional oil - take your pick, but stick with the one you choose and change it at least every 3,000 miles and you'll be fine.

Larry Bibles "change it hot/change it often" is sound advise. You'll drain more oil and flush contaminants.

Syn vs Reg.
An ongoing debate:confused:
I agree with the others to a point. I do use synthetics exclusively in all my cars. There is discussion of leakage due to the thinner texture(viscosity) of the synthetic(so I'm told). I have not encountered this on any of my cars. The reason I prefer it is simply a higher breakdown temp. 500deg vs about 300deg for normal oil. I must admit I'm still running original engines on the vettes and they run HOT. It's a matter of choice. Standard good quality oil will do the job just fine. On a high performance engine that gets worked, I would vote for synthetics on any year car.
And most of all, change at 3k and these engines will outlive us all.
Just my .02;)

I remember reading somewhere in this forum that synthetic oil in older cars is not recommended because it can seep through a gasket because they were made of much different material years ago... how long ago I don't know.

Simply use your eyes. Buy the full synthetic, if it leaks, stop using it. Go buy some syn-blend oil, if it still leaks, stop using that. You don't mention how many miles your car has or type of driving you primarily do. I believe full synthetic is best for high reving/hot running engines. I use full synthetic in my Passat, which has the 20V turbo engine. Now both of my Benzes have turbos also, but they don't get anywhere near as hot as the one in my Passat. So I use conventional oil in them. What ever you decide, make sure it is the proper weight. European cars like the thick stuff, be it 5W-40, 10W-40, or 15W-50. Just look at your owner's manual, it will tell you what weight to use based on outside temp. "Change it hot and change it often"

KNanthrup,

I am an advocate of synthetic oils and have been since the mid 70's when it first became available. I have not used anything else on my cars since, especially Diesels. I lived in Alaska then and Mobil 1 was the only reason the car started when it was not plugged in during the Winter.

I have just taken the head off my 1986 190E 2.3-16 to repair a burned exhaust valve. The job is taking forever due to problems with parts availability, but that is another story. I was awed by the condition of the engine when I took it apart. There was a little more discolored oil on the engine internals than I expected, but none of it would not just wipe off. The cylinder bores were like new, original cross hatching from the honing still intact, and no metal ridge at the top of the piston stroke. The piston tops are a little discolored (black) but those are likely deposits from the last ride before the engine was torn down, as it was running really poorly. I have enclosed a photo, and I hope it comes through.

By the way, the car has 206,000 miles on it and this is the first time the head or any other major engine component has been removed. I look at the results as evidence that synthetic oils are in fact better at protecting engine internals from damage in high performance cars or harsh operating conditions (Diesels). The way I look at it, the extra cost is not wasted. Good Luck, Jim

Cheers for the excellent photo!