Originally Posted by
garage sale GT
Borg-Warner specified ATF for use in its T5 manual which equipped both the Mustang and Camaro in the 1980s. I don't follow cars so much anymore but I believe that wasn't the only time a manufacturer specified ATF for a manual. So I'd say i'ts found in "automatic planetary transmissions and NOT in MOST manual "mechanical" transmission."
BTW, what's your point? Do automatics fail sooner than manuals because the gears wear out? If a turning gear is half immersed it's still covered in oil.
No!
I say that manual gearboxes without any hydraulic actuators and pumps (wheels half immersed) are suited for mineral oil like 75w90 and others, and not ATF (it can be used but it would be plain stupid, and stupidity among research and design department can exist in various forms)
Automatics due to the fact that have to control clutches, and band brakes it is a must to use full immersed gears (and brakes and gears and clutches) in oil. That oil is suited for gears and for hydraulic actuators, also it is controlled the friction coefficient so that the brakes and clutches can operate, and is a light oil to operate smooth in tight clearances in actuators, pistons, pumps etc)
In any Renault manual gearbox, you would find mineral only, and oiling by splashing (gears are half immersed in oil). (I design some of Renault manual gearboxes)
As for oiling trough splashing or full immersed, it's better if it's fully immersed in terms of durability, but automatics have a lot more gearing to transmit power, opposed to a manual which has only 2couples of gears for one gear (two gears from primary and secondary shaft, and primary transmission to the differential cylindrical crown), so it has a bit more wear from the complex mechanism, but is a bit better oiled by fully immersed gears, but with a lighter oil than mineral oil that is deficitary at extreme pressure contact lubing (EHD lubing) for gears, but EHD lubing is not such a great deal when the gears are fully immersed. So the result is : it depends.
Generally automatics are more durable than manuals, but you can get much more use out of a manual gearbox since servicing manual gearboxes can be done easily (replacing gears, synchros, shafts, bearings and other things) opposed to automatics which when they break they are replaced and not repaired.
Either way nowadays it's not a problem with gearbox durability either manual or automatic on automobiles.