i have a few questions relating to the recent discussion of engine oil
in transmissions. i have a 1967 triumph 650cc motorcycle which has many
of the same "features" of our beloved lbc's (it leaks, the lucas
electricals are questionable, etc :-) the haynes manual i have been
using specifies 50w engine oil for the gearbox, so that's what i've been
using. i recently got a clymer manual that specifies 90w gear oil, so i
started wondering which was right. the descrepancy was resolved when i
found the following quote in _triumph_twin_restoration_ (the bible):
SAE 50 oil was specified for many years but as the power went up
and heavier loads were generated on the gears this was changed to
an EP90 gear oil. This has a similar viscosity to the earlier
engine grade but is better able to cope with the stresses involved.
so my questions are:
1) are engine oil and gear oil rated so differently that 50w in one has
similar viscosity to 90w in the other?
2) so what the heck is really the difference between engine oil and
gear oil anyway? i had been under the (mistaken?) impression that
the major difference was just that gear oil was higher viscosity.
3) what is meant by "better able to cope with the stresses involved"?
any opinions or insights? or is this just petroleum alchemy that only
students of the black arts have a right to understand?
tim
aka {uunet|uw-beaver|decwrl}!microsoft!timke
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