[Shop-talk] Oil grade selection

[Randall]

> There has
> been much talk in classic car circles about this,

Indeed there has been a LOT of talk, but precious little hard evidence.
Just once, it would be nice for someone to assemble two identical engines
and demonstrate the difference of running a low-ZDDP oil in one, and
high-ZDDP in the other.  The entire ZDDP debate seems to be based mostly on
increased camshaft failures; but the increase in camshaft failures started
BEFORE the reduction in ZDDP!

BTW, ZDDP comes into play when there is metal-to-metal contact, ie the oil
film breaks down.  If full synthetics do have higher film strength, they
should be better able to maintain the microscopic oil film and hence have
less need of ZDDP.

Randall