Glenn Coughenour wrote (on 4/10) :
>
>
> I don't recall if
> you said the time frame, but when PCV's and later when EGR was
> introduced there were many issues like this because that increased the
> oil contamination, both in rate and in specie of contaminant.
My experience with Pennzoil was in the 70's, quite a few years after the
introduction of PCV on 'modern' engines.
A true PCV system should not cause increased oil contamination. That was
more of a problem with the early systems that did not have a fresh air
intake to the crankcase (like those used by Triumph well into the 70s).
Why would EGR increase oil contamination ?
> You might have purchased some oil that was not solvent refined, but I
> doubt that since you seem to be careful to purchase quality products.
Back then, I believed Pennzoil and Quaker State were quality products.
After having the experience of removing the pan from an engine that used
them, and finding the bottom of the pan coated with a thick layer of grey
sludge (on an engine with neither PCV nor EGR), I no longer believe that.
Having noted that my TRactor motor would "wear out" viscosity improvers in
as little as 2000 miles back then, I wonder if it would also break up those
branched paraffins you mentioned, leaving them as straight (lighter)
paraffins that could clump together and form sludge. In any case, I know
what I saw, and I know that Valvoline doesn't do that. Theories are nice,
but when they don't match the real world ... guess which one has to change !
Randall
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