Subject: RE: Transmission oils.
Date: Feb 1992
On the subject of transmission and rear-end lubricants ....
Some years back, I bought an ratty old Bavaria; the previous owner had
been using it as a pickup truck, judging from the number of rusty nails
I found under the spare tire.
The transmission was rather loud, too; it didn't make any _bad_ noises,
it just whined, rattled, and generally b!tched about its role in life. I
figured it had the wrong oil, or not enough of it, so I went over to a
friends Jaguar-only garage to "rack" the car and check the tranny oil.
"Just change it," said my friend. "Here's a giant allen key. Always
take out the filler plug first; if you can't get that out, don't drain
The filler plug came out OK, but the tranny was really hot. I expected
to deep-fry my hand when the hot oil from the drain plug came out.
Not to worry. There wasn't a drop of oil in the whole damned gearbox.
So I called one of the local BMW garages and asked 'em what to do.
"Does it work OK when you drive it?"
"Can you see the gears up inside the 'box?"
"Yeah, and they are kinda blue."
"If they are still darker than Paul Newman's eyes, just fill it with
oil and drive it."
"What kind of oil?"
"Use rear-end dope if you have it. It won't leak out so fast."
So, 90W hypoid oil it was, for the next 60,000 miles. It worked fine.
I sold the car for more than I paid for it, BTW.
"Hypoid" oil varies chiefly from other heavy oils in that it has special
additives (EP or "extreme pressure") to cope with the sliding friction
present in hypoid-bevel rear-end gears. Normal transmissions don't have
this type of friction, so the EP additives are somewhat wasted. In
fact, the main sliding friction in the manual gearbox is the
synchronizers, who depend on sliding friction for their synchronizing
effect, and EP should, in theory, make them _less_ effective rather than
However, I've used 90W hypoid EP oil in all sorts of gearboxes, and it
has worked fine in every case. The extra viscosity of the oil (versus
30w or ATF) seems to make everything turn at the same speed when it
can, making the synchros more of a fluid coupling, I suppose.
That having been said, though, _never_ use thick oil, especially EP, in
'boxes with Laycock de Normanville overdrive units (Volvos, most
Britcars) as the oil pump won't like the viscosity and the EP additives
won't do the friction bands a bit of good. I wouldn't use it in any
pressure-lubricated gearbox, either, like the 5-speed used in Triumph
TR-8 and Rover RWD cars.
Regardless of my favorable experience with EP in manual transmissions,
though, I'm going to try Redline MTL in my 732i next time I change the
'box oil, probably at the 195,000 mile service check.
BTW, the 17 mm Allen key "VW Transaxle tool" (in giant "L" form) is
available at most car parts places for a few bucks. I've never bought
one, though, because everyone who has a grease rack seems to have one!
Date: Thu Jun 18 14:16:04 1992
Subject: Re: transmissions once again
>I don't know the numbers but I would think the viscosity levels between 90wt.
>and ATF would be quite different. There's also a diff. between type F for
>Fords and another for GM cars. I believe the F-type can eat types of seals.
>I've heard you can put a quart into the motor before an oil change to clean
>up the sludge in a motor a bit. (run a 50 miles, drain, fill, drain
>refill, done) Can anyone else verify this? Any articles, etc? My tranny
>on my jeepster grinds going into second when it warms up, not when it's
>cold but I don't like doing experiments that might cost me lots of $$$.
Another of life's little speed secrets is out. ATF works very well in
both trannys and diffs. It significantly cuts down on drag loss.
For no particular reason I've always used Dextron type fluid. I usually
dump a bottle of extreme pressure additive in the rear end, mostly
because of lingering guilt for violating "the rules" back when I first
started doing this.
As to dumping it in the crankcase in order to free up sludge, ahem, why?
Why would anyone want to loosen up sludge securely deposited on various
surfaces and suspend it back in the oil? Let it be until you tear the
engine down and properly clean it out as part of an overhaul.
X-Source: The Hotrod Mailing list
Date: Oct 1992
Subject: Re: Redline MTL
[Amazin' how we get brainwashed about these things. Think about it for
a minute. Ignoring the clutches for a moment, what does the automatic
and the manual have in common? Yep, gears, bearings and sliding surfaces.
Which has the higher specific loading? Think about all those little
planetary gears in the auto. A manual is a cakewalk in comparison.
ATF is pretty amazing stuff. Just about as thin as water and yet
OK. My brain's almost in the dry cycle. :) What about ATF in the motor
[Problem is most of the organo-metallic additives that make ordinary
oil into Superoil burn to form low melting point and/or conductive
ash. Either is pretty bad for the combustion chamber. Any ash is
desired to be non-conducting and high melting point so the ash
will leave the chamber as solid particles and that which melts on
things like the plug electrode at least won't short the plugs. JGD]