DeTomaso Mailing List: July 99, Message #342

Hi guys,

Lifted this from the Nor-Cal Shelby club forum--the words of one of their 
most respected tech gurus, Don Wolleson.

FWIW, well over 50% of this club open tracks their cars, they run them HARD!!!

Mike

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All:

My opinion on Aaaahl and temperature goes like this.

I don't ever want to see ANY oil temp on my car go over 250F.

Viscosity goes down as temperature goes up ... or the hotter it gets, the
runnier it gets. At 250F, even gear lube gets real runny.

You can get TemplStik (sp?) to dob on or stick on to things. The indicator
(usually a special wax compound) changes if its stated temperature is ever
exceeded. If you have lubricant smoke coming out of your tranny or rear end
(or engine), that's a good clue to try some TemplStik (e.g. 250F) on the
gear case to see if that temperature is exceeeeeeded.

If it goes over 250F, I would think real serious about getting a cooling
setup for the diff or tranny. A good synthetic also helps.

Engine Aaahl:

In the case of non-synthetic multi-vis engine oil, the polymer additive
molecules "unwind" as they heat up which mitigates the viscosity drop as
temp goes up. Somewhere above 265F, these magic molecules are unwound all
the way and then as temp goes up some more, they wind themselves back up
into little balls real fast and your lube turns into the consistency of
water. Heavy bearing loads also shear these big molecules into little ones
which causes a permanent reduction in lube viscosity. So these marvelous
street-motor multi-vis oils are not good for open tracks and go-fast
engines. Go single viscosity or synthetic. Synthetics do not have as good
high pressure capability as single viscosity non-synthetics, which means if
you have a flat tappet cam with mongo valve spring pressure, avoid
synthetics. Otherwise synthetics should be preferable.

If you get yourself an electric oil temp gage, you can get the gage, three
senders and a rotary switch and use the gage for engine, tranny, and diff
oil temps depending on where the switch is pointed.

Don Wollesen