Well over the weekend I spoke to a scientist for a major oil
company.
She tells me that 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 sens 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. I'd hazard a guess that
in a number of 'hot spots' in the engine 88C would been seen on a regular
basis in normal driving. Heck, the coolant temp is above that for a
significant
portion of time!
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
-----Original Message-----
From: David F. Darby <darby@tri-lakes.net>
To: Mike Gigante <mikeg@vicnet.net.au>; WSpohn4@aol.com <WSpohn4@aol.com>;
mgs@autox.team.net <mgs@autox.team.net>
Date: Saturday, 13 March 1999 13:52
Subject: Re: Oil Coolers
>Hello:
>
>I have been monitoring my oil temperature for some years now in my 1967
>MGB-GT (standard specs, +.030" bore). It is a daily driver with the
original
>oil cooler as fitted at Abingdon.
>
>I run 20W/50 Castrol and live at 1,200 feet above mean sea level in the
>Ozarks of Southern Missouri (USA) at about 37 degrees N latitude. My
driving
>is exclusively rural on secondary roads with lots of hills and curves. The
>car now has logged 282,000 miles since new with one major overhaul at
>200,000.
>
>Winters here are usually moderate although below 0 (F) temps are normally
>encountered once or twice during the winter. I run a 180 degree F
thermostat
>year-round. I have made an insulated shroud that completely covers the oil
>cooler for winter use. Cold weather temps on the gauge run about 140 F.
>
>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.
>
>Regards,
>
>David F. Darby
>http://www.geocities.com/MotorCity/Downs/4598
>
>-----Original Message-----
>Mike Gigante said:
>> Subject: Re: Oil Coolers
>
>
>>This argument is easily solved. Buy an oil temperature gauge, install
>>it and report the findings to the list for a B driven in "normal use"
>>(whatever
>>that is). Please also tell us what the average ambient temperature is.
>>
>>Seriously, if your driving style and the weather around where you are
>>are likely to result in an engine which runs quite hot, then an oil cooler
>>is a cheap and worthwhile investment. Oil that is too hot breaks down
>>and not only provides inferior lubrication but acidic by-products. So
>>an oil cooler can be well worth it. If you aren't sure you can put in an
>>oil temp gauge!
>>
>>Note that 100% synthetic oils exhibit this breakdown at significantly
>>higher temps.
>>
>
>
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