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RE: Oil choice

To: "fot" <>
Subject: RE: Oil choice
From: "Randall" <>
Date: Wed, 8 Feb 2006 07:59:09 -0800
>     Has anybody heard that they removed Zinc from most new oils and that is
> one of the problems with the majority of oils and our old bearing material.

I knew that they lowered the standards for levels of zinc in motor oil years
ago, not long after catalytic converters came on the scene.  Comparing the
numbers on Valvoline's web site to the venerable motor oil FAQ, it appears that
the standards have been lowered again in the last 10 years or so.  Probably some
environmental nut got worried about all those "heavy metals" being dumped back
into the environment they came from, without considering that zinc is essential
for life.

> What does the Zinc in oil do
> anyway?

It's a compound, zinc dithiophosphate (or something like that) aka ZDP.
Supposedly, it plates a thin film of itself onto rotating parts (like crank
journals) that can then act as a sacrificial layer in case of metal-to-metal
contact.  I'd guess that more careful crank & bearing design in modern engines
has more to do with not needing zinc, than bearing material.


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