" larger amounts
of sludge when using motor oil that claims to come from "Pennsylvania
grade
crude".
Someone else mentioned that Pennsylvania grade crude oils have a high
ash content, but the stuff that collected as sludge is generally a
combination of that ash [that "seeds" agglomeration], oxidation products
and other reactions of the oil and its additives with blow-by gases and
gasoline that it contacts on the cylinder walls. What is commonly
called wax are linear paraffins. As I said in the earlier post, these
are extracted. Pennsylvania crude does have more of these to extract.
The branched paraffins remain. That is what is meant by paraffinic oil.
The branched molecules are unlikely to produce wax because the branching
prevents them from getting close together. My guess is that it had more
to do with the additive package than the base oil. 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. It took a
bit of experience in the industry to adapt. While companies like Quaker
State and Pennzoil had better base oils by virtue of their well
locations, they never had the R&D strength that Mobil and Exxon [now
ExxonMobil], Shell and other major oil companies had. As a result, they
couldn't keep pace with the engine changes as well and at technology
transition points their products sometimes faltered. In today's
engines, the additives are more important than the base oil, until you
make the leap to synthetic bases that are not sourced from petroleum
directly. In our LBC's these differences are less pronounced.
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.
Glenn C
1959 TR3A TS31684L [in total frame up restoration]
1960 TR3A TS64803L [driving, but needs work]
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