>When I approached Castrol requesting an opinion about why there was a
>difference (and it was from its reply that I learnt that 80W/90 was
>"thinner") the reply was a bit cagey as the did not want to refute a
>manufacturer's recomendation. The reply went on to describe the different
>properties needed in a gear oil to an engine oil and it is not difficult
>appreciate why the requirements are different. For example a gear oil needs
>very little detergent action since there is no polluton from gases etc.and
>has to be very non foaming. However, the oil does need to adhere to metal
>faces on gears and withstand very high temperatures caused by the friction
>in a gearbox under high loads and so is made for the task. It is probably
>the latter consideration which made MG specify it for the V8s but never for
>the four cylinder models right up to the end of production.
One point that has not been addressed in this thread is whether there would
be a preference based on O/D considerations. A little ignorance: Did the
V8 come with O/D optional, or only O/D? I have a C that is a little hard to
shift, so I fall between the I4 and the V8 in the gumption department.
Synthetics are too slick for the O/D. Wonder if the 80W/90 would be to
slick......
Mark A Dodd Working in the dark (infrared)
email: dodd@el.wpafb.af.mil Working in the grease (MGs)
Snail: 2700 D St, Ste 2 Working in the dust (212 Central
WPAFB, OH 45433-7405 Dayton, OH)
(513) 255-5581
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