[Swepco]

Greg,

Your response to your friends about using multi-vis motor oil in transmissions is right on the money, however, being old-school as I am, I really don't believe in using ANYKIND of engine oil in transmissions....engine oil is for engines, transmission oil is for transmissions.

To be sure there is a lot more shearing going on in manual transmissions than there is in engines, the multi-vis oils will shear out faster than straight weight oils will because of the VI improver, but there are also other factors to consider as well.

Engine oils have a completely different chemistry than transmission oils have, they use a different blend of detergents for one thing and are made to hold water in suspension until it is "cooked-out" from the heat of normal engine operation.

Years ago, heavy-duty manual transmissions called for straight 50 weight, non-detergent engine oil instead of gear oil. Also, at the same time many others, especially the European Car manufacturers were recommending 90wt "GL-4" gear oil for their fussy transmissions. Both of those recommendations are the same viscosity and neither one of them have highly active sulphur-phosphorous compounds which can attack the yellow metals in the syncros. SWEPCO's GL-5 gear oils are compatible with yellow metals and are commonly used in applications which call for GL-4 Lubricants - primarily because you get the added benefit of having extreme pressure additives.

Here's where the confusion comes in.....you must know if your transmission manufacturer (or builder) recommends gear oil, or a lighter weight oil similar to an ATF. Once you know this, using a high quality product which contains extreme pressure additives will give you the correct shifting characteristics and afford the best protection for the transmission. Transmission failures can really be ugly from financialy as well as the physical, including breaking down somewhere out in the toules when you are out there "having fun."

SWEPCO manufactures straight weight gear oils as well as multi-weight, but my favorites always have been the multi-weight, either the 201 - 80/90, or the 210 - 80/140. If you experience a lot of off-roading, or heavy footing, the 210 would be my first choice, and it is more energy efficient than even the 201 - 80/90 is. Another plus for using one of these is the fact that you can use the same oil in the differentials. If you are designer prone, the 201 is dyed Blue, and it is commonly referred to by users as "blue-goo" because of it's tacky characteristics when cold. The 210 is dyed Red, but it doesn't have a fancy name like "goo" (besides goo doesn't rhyme with red).

As far as the lighter weight ATF type oils, SWEPCO 714 - 20wt or 30 - wt oils would be the way to go, but bear in mind that the 30wt might be a little more stiff shifting in colder climates. The 714 oil contains extreme pressure additives as well.

Anyhow, that's my take on using what I feel is the correct oil for the application.....hope it helps!

Dick Floryanowich