I made the original comment, cause that's what I'd heard, and another poster
chimed in with the idea that the scales were actually the same, but the
temperature that the measurement was made at was different, because of the
different applications. One thing to keep in mind is that in 1959, when the
20-50 oil recommendation for tranny oil was made is that they probably
didn't have all of the detergents, etc., in the engine oil that they now
have. If that makes a difference, I don't know, but I still use fully
synthetic tranny oil in my gearbox. Also keep in mind that differential oil
must be hypoid gear oil, while tranny oil shouldn't, or at least doesn't
have to be. The Tranny oil that I use is designed for racing motorcycle
transmissions, and notes on the bottle that it's not suitable for hypoid
gear applications, so there must be a difference.
Also keep in mind that the gear box in the Mini (3 synchro version) is
identical to the rib-case gearset (the gears are interchangeable, with the
exception of the input gear), and the Mini transmission runs in the engines
sump, on 20-50 engine oil, but the oil is changed far more often than
typical tranny oil.
At 04:18 PM 3/18/98 -0500, you wrote:
>The note earlier on this list said that engine oil and gearbox oil were
>rated on two different scales. That, in fact, 90w gear oil is the same
>viscosity as 30w engine oil.
>Chas Douglass -- Seattle Wa
>Foxy Dave wrote:
>> If this is true ...
>> > I replaced the gearbox oil with synthetic 75w-90. Very nice change!
>> > Thanks for the suggestion, whoever it was that mentioned it. Smoother
>> > shifting and quieter when hot. One of the nicest easy (other than
>> > getting that damn fill plug started back on it's threads) changes I've
>> > made for driveability.
>> why do the books say to use 20/50w motor oil in the trans ?
>> I'm tempted to change over 'cause it seems to make good sense to give the
>> gears a heavier oil ..... doesn't it ?
>> Does anyone have a good argument to the contrary ?
>> Nice tool invention Crash !
>> Please put me on the waiting list for purchase ;-)
>> At 10:49 AM 3/18/98 -0800, David Ramsey wrote:
>> >Hi Chas,
>> > I have invented a high tech tool that aids in the removal and
>> of the tranmision fill plug.
>> >> I replaced the gearbox oil with synthetic 75w-90. Very nice change!
>> >> Thanks for the suggestion, whoever it was that mentioned it. Smoother
>> >> shifting and quieter when hot. One of the nicest easy (other than
>> >> getting that damn fill plug started back on it's threads) changes I've
>> >> made for driveability.
>> > I will be selling these "Pat Pend" tools for the low cost of 29.95 +
>> shipping, as soon as the tooling is done. This special tool consists of a
>> 2" piece of high tech 5\8" rubber hose "heater or garden". All you need to
>> to do is loosen the drain plug with socket wrench and place the special
>> tool on the plug and remove by hand, to replace the drain plug you just
>> place the special tool "Pat Pend" and drain plug on the transmision and
>> hand tighten, remove the tool and snug-up the plug with the socket wrench.
>> > At this time I have several hundred of these tools in stock (the
>> my 5/8" sears garden hose got run over by my bug-i). However shipping will
>> be delayed about 6 months, because I am waiting for the paper "Made in
>> England" stickers to arrive from England.
>> > Crash