dicer

True about the grease zerk if they had one. That transmission takes T-IV nothing else, huge mistake putting in some off brand, like maybe you can get away with on something newer or other brand of vehicle. If all parts are brand new in a transmission and have not seen a drop of fluid before you could use what ever you like. Then the only problem is the transmissions programmed shift schedule that is where a certain friction modifier and quantity there of is needed. Lots of people that are not in the know think what I said is BS. Call a manufacture of automatic transmissions and talk to a lead engineer to have him explain it.

TheDoctor

Good advice. You can't go wrong with the factory fluids. Simply a good lubricant base stock is necessary, but as you point out even more critical is the additive package. Friction modifiers are critical to transmission operation and longevity. For example: My 93 MR2 manual trans recommends 80w-90 GL3 gear oil. However almost all 80w-90 gear oil you can find these days is GL5. Sometimes GL4. Both are far too "slippery" for the synchronizers to provide smooth gear engagement. Both can also be corrosive to copper and brass alloy components. Automatic transmissions are even more selective about their fluids. Fibrous clutch disks and bands, bathed in transmission fluid grind like brake pads against steel plates and drums providing the gear shifts your too lazy to do for yourself. The oils job is critical.

dicer

Your right GL5 is really only needed in high pressure high sliding contact like hypoid gear sets found in differentials, and like you say the EP added to it is not too nice on the syncro alloys.

TheDoctor

I've seen nearly every incorrect fluid mistake that can be made. Since Leaving the Army in 1994, I've made my living as a mechanic. Cars for a while. Commercial trucks for a time. Then back to cars. Some were remedied without too much drama. A few memorable ones were:

Fuel stuff:
Diesel in Gas tank. Won't run. You have to clean it all out, from the tank to injectors. Isn't cheap. Usually no big harm done.
Gas in Diesel. Might not run, depending on engine. If it does run, it won't for long. Lots of harm done. Your most likely screwed.

Transmission:
Dextron III in a Honda CVT. Sadly, the owners had just bought the car and thought the transmission was slipping. So they thought changing the fluid would help. (It never will) The shop they took it to, had never seen a CVT and hooked their flush machine up servicing it with Dex III. This eventually required a new transmission.

80w-90 GL4 in a ZF 5 speed manual requiring ATF. The synchros refused to syncro at all. Returning to the correct fluid helped, but the residual high pressure lubricant additives from the gear oil could not be flushed out. The front and rear seals began to leak soon after. Only a rebuild put this one right.

CELSI0R

Wow, that's a pretty cool background!

You just reminded me about the whole deal with Dexron being put in Chrysler FWD transmissions instead of ATF... The dismissal of those little details led to a pretty big misconception about reliability.