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Re: Trans lube/Engine oil

Subject: Re: Trans lube/Engine oil
From: (Graham McCann)
Date: Fri, 15 Mar 1996 09:48:18 +1100 (EST)
>Have followed gear lube threads and now that everyone knows how to get it
>in the transmission some other thoughts:
>     I'm trying to get exact specs but I think I remember from somewhere
>that 80-90 weight gear oil has about the same viscosity as 30-40 weight
>motor oil.  Apparently the powers-to-be gave gear oil different
>nomenclature so Bud or Earl didn't fill your engine crankcase with it.
>     I've had several NON-OVERDRIVE mgs which have had both gear oil and
>engine oil in the tranny at some time.  Although the book calls for engine
>oil I wouldn't worry about gear oil in your transmission (non-overdrive).
>     What I've done is switch to Mobil 1 15/50 synthetic oil in both my
>engines and the tranny of my MGC (my TC uses 140wt ).  These are low
>mileage cars and this way I usually change the oil yearly.  The 15/50 flows
>at a lower temp than conventual 5w/30 so is great if you want to crank your
>car up in the winter.  High temperature performance exceeds conventual 40
>or 20w/50 oils.  If I burned or leaked a lot of oil it wouldn't be cost
>effective but for me it works out.  Amsoil also makes a 20/50 synthetic but
>its even more expensive than Mobil 1 and I can't figure out their Amway
>style marketing system.
>     Both engine crank great whatever the temperature is, oil pressure
>doesn't seem to vary with high temperatures and the transmission of the MGC
>seems quieter and shifts better with the synthetic.
>               Bob Skillman (47TC,68MGC)
Everything you say is correct and I have official Castrol bulletins to
suppport it but I am curious why you appear to dismiss 80W/90 for overdrive
equipped cars.  The MGB GT V8 manual in fact specifies the use of 80W/90 oil
in the gearbox (and they all had overdrive) and you will find that Triumph
and Jaguar specified 80W/90 for overdrive models.  Some people here use Auto
Transmission Fluid with considerable success, although I tend to stick to
the manufacturer's specs.

Graham McCann  Rivett, ACT. Australia
06 2889055

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