Engine Oils Fact or Fiction

[Bill Verburg]

Originally Posted by pmax

The "dude" is a pro mechanic shop.

ZDDP was brought up by the replies here not them.

If opinions from those who rebuild engines don't count, whose does ?

By far the primary controversy wrt to oil standards was the Federal mandate reducing ZDDP in some oils back in 1996 when the API SJ standard became effective. There have been no recent relevant controversial changes though we are up to API SN now.

secondary was the controversy of using multiweight oils back in the 60s and 70's

The topic just naturally arises in oil threads because all light weight motor oil and some heavier weigh motor oils did reduce ZDDP and it did cause some problems w/cams in air cooled 911s

There have been changes int he standards in recent years mostly wrt direct injection engines and other technologies not relevant to old air-cooled designs.

There are ?Pros? and then there are Pros!!

Most of the rplies are on topic and are tring to be helpful

[stownsen914]

Um, I didn't say he said anything about ZDDP. He seems to be claiming (granted second hand) that modern oil is causing rod bearing failures. Which doesn't really make sense.

Separately, people in this thread brought up ZDDP, which though important, is unrelated to rod bearing failures.

Is that better?

[Jeff Alton]

Correct ^^^^^ Bearing failure is different. Improper assembly and measuring is usually the cause. However, assuing a proper clearance check, and instalation, Rod bearings get hammered by too much compression or more often too much ignition advance.

Would be intersted in seeing what side of the bearing (top or bottom) was showing the most wear.

Cheers