Hi Tom,
Our engines are pretty loose by modern engineering standards, so the
thicker oils sort of fill in the gaps, providing a thicker surface film.
These newer engines really are remarkable. Wonder what oil is
recommended for the MGF?
Much concern exists over the dry starts from oil dripping off rubbing
surfaces. My practice for years is, if the engine hasn't run in a week or
so, to spin the TD engine with the starter until pressure registers on
the gauge, then to turn on the ignition and start it up. This May, I
removed the sump from the engine, which had not run since December. I
found oil drops clinging to everything-pistons, cylinders, rods, etc, and
there was a good slippery film on the cylinder walls. Perhaps without
reason, I had been expecting to find dry surfaces, but they were not.
10-40 is looked on with suspicion by many, for the reason that the
viscosity index improving chemicals are said to break down more rapidly
than on 10-30. I would use the 10-30 if starting and driving in 32
degree weather, and would stick with the 20-50 for summertime use. The
workshop manual recommends it, so one supposes that it was the right
grade for England, where temps never get very high.
BTW, many light airplane engines use straight 50. If dry starts are a
problem, they must have metal filings puffing out the exhaust after a
week in the hangar.
Perhaps someone who knows more about oil chemistry can tell us more.
Bob
On Wed, 10 Sep 1997 07:23:47 -0400 (EDT) Teacher122@aol.com writes:
> DUH! It took me forever to figure out how to post something in
> You'll love this last topic! With almost all modern vehicles
>running
>on 5w-30 oil and easily lasting 100,000 plus miles before major engine
>work,
>why are we running our MGs on 20w-50? Is the oil so thick that oil is
>not
>reaching engine parts during critical moments of cold starts? Would
>a
>10w-40 oil be a better choice especially during the colder seasons?
>Is
>anyone out there running a different grade of oil besides 20w-50?
>What's
>your experience? Maybe it's just the fact that 20w-50 leaves smaller
>puddles
>on the garage floor. We've discussed the "hearts" of our cars enough
>let's
>go for the "blood" now.
>
>Tom Green
>1979 MGB
>
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