Well I tried my experiement and put Mobil1 ATF in my 6 speed. It shifts smoother (again) and appears to like the stuff. The Amsoil 80w-90 that came out looked funny as if it was full of metal dust or something. That of course wouldn't make much sense because the 6 speed has a big magnet inside it to attract the debris.

I did notice at first that my worn out 3rd gear syncrho was behaving far worse than before but after only a few miles it was working as it did before the fluid change.

This is going to require a longer term test for viability but for now the thing seems to be almost BMW smooth. Which is where I got the idea from, BMW uses ATF in their brand new manual gearboxes.

 

Hmmmn....what are the risks to using ATF instead?

 

If the fluid is not compatible with the metals inside the tranny, it will eat it up.

 

Less shear strength and protection under high stress applications. Flows better in cold though. Most ATF's have a viscosity similar to 5W-20 motor oil.

It will be interesting to see how it holds up in this application!

 

just wonderign how the tranny is holding up

 

it blew up 15 miles later and the flying gears hit and paralyzed the driver/poster...

 

Are the American Racing Chrome wheels there to prevent people from getting near your car, theft deterrent?

 

That transmission had previously suffered many 5k+ RPM launches on slicks, prior to the ATF experiement and 1st gear eventually let go. But overall I would say it wasn't a good idea, not because of lack of lubrication but because of the lack of shock proofing.

 

Are there any additives on the market that could raise the viscosity and/or improve the shock-proofing properties?

 

Not that I know of, I just wouldn't do it anymore.

 

Redline has a few:
http://www.myoilshop.com/ShkProof.html

 

I think he was talking about shock proofing ATF.

 

Some manuals are meant to use ATF from the factory. My one friend's Mustang's 5MT (2000) uses ATF, as does another buddy's Firebird's 6MT (1994). I was surprised, as I thought ATF would be a little too thin for gearbox applications. I also thought ATF to be similar in viscosity and weight to 5W-20.

Personally, if the car had 80W-90 in it from the factory, I would definetly not go to a dramatically thinner oil. I know I can't afford to risk having to replace a transmission.

 

Most domestics (tremec based) use ATF in their manual transmissions.


If Matt really got the idea from BMW he would try to seal Automatic transmissions making the fluid non serviceable

 

Lifetime ATF BMW transmissions are still serviceable.

 

not if your a BMW tech