Hmmm, this goes against some of the things I have heard in the past.
Isn't it normal for the oil in an engine to be hotter than the water?
190F is a normal coolant temp, I would think that the oil is much hotter
(don't have my oil temp gauge installed yet).
I was under the impression that the oil had to get this hot for water and
other things to evaporate out of the oil. I seem to recall a oil temp
target of 210 to 220 degrees, but I can't remember the exact number.
If this is true, your point 1) would not be a good idea (keeping oil temp
under 190F). But would anyone really use mineral oil if it was
experiencing constant and significant breakdown with serious consequences
at normal operating temperatures?
I am not arguing very scientifically here, but something doesn't seem to
add up, maybe a piece of information is missing.
Ulix
On Mon, 15 Mar 1999, Mike Gigante wrote:
> 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
>
>
>
>
Ulix __/__,__ ___/__|\__
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'67 Sprite '74 X1/9
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