Over on the MGs list, there has been a discussion of the usefulness
or otherwise of oil coolers on the street.
One lister, David Darby, reported that
"During summer operation ambient temps can reach 100 F or more. August is
our
warmest month with daily high temps averaging about 95 F. The highest I've
seen the (Stewart-Warner) oil temperature gauge go is about 195F. It
normally runs 160F to 180F. I am measuring the oil temperature at the union
between the return oil line and the engine block.
Those are my half-baked observations on oil temp in my own MGB. YMMV."
Note that David is running an oil cooler and that the oil temp gauge is
sampling temperature immediately after it has been through the oil cooler.
Over the weekend I spoke to a scientist at a major oil company and this
is what she had to say:
"Mineral oils start to break down at 88C (190F) whereas synthetic oils
begin to breakdown at 200C (392F).
Byproducts of mineral oil breakdown include acids and carbon soot.
The carbon soot tends to fall out of suspension causing deposits
throughout the engine.
Byproducts of breakdown in synthetics remain in solution (hence no
deposits)."
So, I think this clearly sends two messages
a) if you use mineral oils, an oil cooler is a pretty damn good idea
if your oil temps are likely to approach 88C. From David's data, it seems
very likely that a significant portion of listers will see this on a regular
basis.
b) you should seriously think about using synthetics! I have been doing
so for the past 5 years or so and I have no complaints!
Mike
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