> > back from the land of the body men and have my first questions. There has
> > been a lot of talk lately on the M***a list concerning transmission and
> > differential fluids. Now is the perfect time for me to change these
> > fluids in the B. Actually, the tranny has been rebuilt but is dry. The
> > rear axle is in the car. Any recommendations on lubricants for these
> > two units? I know what Haynes recommends but I wonder if there is some
> > net.wisdom on this matter
>
> Go with what the manual says for the transmission, especially if it
> recommends engine oil. I like Redline Hypoid for the diff.
The B's gearbox uses motor oil of the same weight as that in the
engine. The principle is that while the gears require higher shear
strength because of the direct pressure that the engine doesn't get,
they also operate at a lower temperature where the oil keeps a
higher viscosity. The only issue then becomes temperature/viscosity
range for your weather conditions.
My recommendation: Castrol Syntec 5W-50. I'm currently running that
in the engine of my non-British sports car, and I've been very pleased
with it. The main advantage is its ability to flow when cold, something
that I'd think would be especially important in a gearbox; it's also
said to be designed to cling to surfaces to provide some protection
against the flip side of pourability (remember the commercial where they
drain the oil out and the motor keeps running?) A 5W-50 should cover
pretty much any temperature spread in North America, at least those
temperatures in which you would want to drive an M.G. :-)
Offsetting the price is the fact that a) you don't use much of it, and
b) you don't change it often. I'd suspect, in fact, that you probably
never have to change synthoil in a gearbox, for the simple reason that
the only reason you change synthoil in an engine is to get rid of the
combustion by-products; modern synthetics, for all practical purposes,
do not degrade sufficiently to warrant dumping them. But if you leave
the acids, varnish, particulates, and crud in the motor -- even with
regular filter changes -- you'll attack the seals, and eventually even
the metal, and corrosion will set in. Since that doesn't happen in
the gearbox, you can pretty much dump it in and forget it.
(Well, except for what leaks out. But rebuilt M.G.s *never* leak,
do they? Aaargh... At least I know *where* my leak is. Now all I
have to do is find the time to fix it!)
--Scott "And fortunately, the motor doesn't have to come out" Fisher
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