At 11:09 AM 6/4/2011, Dennis Haynes wrote:
>With today's modern oils there is no reason to have to go to the
>straight 40 for any temperature. I don't even know straight weights
>are available with the latest specifications. 20w-50 or 15w-50 will
>work just as well.

But you agree that 15/20W50 is correct oil for *all* WBX in cool to
very hot temps?  According to the spec 10W30 or 10W40 is only good to
60F.  Or is that requirement also relaxed?

I want to push on the "straight-40" for a moment.  Looking at the
chart for '89, they specify 10W30/40 up to 60F but straight SAE 30 up
to almost 90F.  It seems to me there's a case to be made in hot
weather for oils that don't owe their high-temperature properties to
a bunch of very-long-chain molecule viscosity improvers that degrade
over time as they get sheared in the engine, and degrade rather
abruptly when they get overheated.  Using a single-weight oil gets
you back to the more robust - I *think* - chemistry of short-chain
hydrocarbons.  And the engines were built to SF, so an oil meeting
that spec should be sufficient.  What do you think?

Castrol HD40 "exceeds SM, SL, SJ" and "is engineered for greater
protection against thermal breakdown."  Key benefit is "provides
maximum wear protection in warm
climates."
http://www.castrol.com/castrol/productdetail.do?categoryId=9020528&contentId=6031112

Here's one from an oil-rig pump builder for use in their own systems
but recommended for the universe, meets SJ:
http://www.tescocorp.com/data/1/rec_docs/321_83200e.pdf

Royal Purple has one, Amazon says "API certified..." <roll eyes at
Amazon's idea of specs>  Also says their (R-P's) most frequent
customer comment is how they can feel the difference in their vehicle
<roll eyes at Royal Purple's idea of
credibility>
http://www.amazon.com/Royal-Purple-Synthetic-Engine-Bottle/dp/B000BRRI02

Yours,
David