on 11/7/03 10:50 AM, Charles & Peggy Robinson at ccrobins@ktc.com wrote:
> Well, lessee, in an overdrive friction clutch, isn't the oil under
> shear forces? And the oil is at high pressure in the overdrive when
> it's engaged. Isn't that good?
It's not that the multi-grade viscosity enhancers are in themselves bad --
it's that they are unnecessary. As are the detergent additives. And my main
point was that both of these break down long before the regular gearbox oil
change interval.
>
> I've been using 20W-50 in MGB overdrives for 10 years or so. No
> failures yet. Isn't that good?
Yeah, but it could also be interpreted as a testimony to the robustness of
the overdrive...
>
> What I don't understand is why you don't believe that the guys who
> designed and built the gearboxes/overdrives didn't know what oil was
> best to use in them.
Because multi-grade oil DIDN'T EXIST when these were designed, so they were
obviously NOT designed with it in mind. The fact that BL, after the fact,
included it in their recommendations doesn't mean they understood the
issues; judging from their track record, they probably just took the
easiest/cheapest way out, or jumped on the new trendy bandwagon, or just
figured it didn't matter.
And it doesn't matter all that much, I suppose. But if 30wt is just as
effective for the purpose, and lasts longer, and is also cheaper, I don't
understand the blind insistence on using 20w50.
--
Max Heim
'66 MGB GHN3L76149
If you're near Mountain View, CA,
it's the primer red one with chrome wires
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