I just got an eaton posi unit, and it says it doesnt recommend synthetic lubes. I got an install kit as well that comes with redline gear lube. Should I use it, or get something else? Also, any opinions on the best tranny fluid for my a4?

 

Probably not the best topic name for your post brah.... Sorry, couldn't resist..

Ken R.

 

i didnt see that till now. Thanks for pointing that out ill rephrase that. Best fluid for rear axle, and tranny

 

Synth is too slippery for a friction type posi like the Eaton. Synth is a waste in a rear end anyway, IMHO. In the motor, it's another story.

Rich

 

Agreed. Thats the same reason people recommend that you don't use synthetic in A4 applications.

 

synthetics are just man made oils that stand up better than any conventional oil could ever withstand. i believe i would put synthetic diff fluid in before the engine. it is free horspower. grab a bottle of synthetic and a bottle of regular gear oil and look at the free flow ability of the synthetic. picture that inside a diff. the difference is like swimming in molasses or water. synthetics are an easy 5-10 rwhp. besides almost all the manufacturers are factory filling rear diffs for the mpg and wear. if the factory is doing it and paying more there must be an obvious advantage.

before you stone me to death i suggest you check out performanceoiltechnology.com. it is a great website with some good info.

as for transmissions i would recommend synthetics also, especially in older 4 speeds. i use amsoil and was a die hard mobil fan before that. i picked up almost 14rwhp in my truck by switching my diff and engine from mobil to amsoil. truck was only 153 to start

 

i would call eaton and ask what is recommended and why. some posi units require additive specific to the diff. but regular gear lube does not have it either.

 

Im just wondering b/c I got the rear end install kit from thunder, and it came with posi add. and /or red line, royal purple diff. oil. I read my eaton posi box, and it said that the use of synthetics is not recommended.

 

The use of synthetics in a limited slip rear is dependent on the friction material used in the clutches. New diffs use a different friction material in their clutches (zexel torsen for instance) than do other companies(auburn or eaton)....if the eaton instructions call for a standard mineral oil use it or you could have excessive clutch slippage

 

i got ahold of eaton and they said it depends on the diff. some use carbon fiber and some used (standard) clutches. they recommended using what was in the instructions. i have a posi coming tommorow and they said to use lakewood mineral based fluid because the additive is in there. not all thier posis are the same. use only what was recommended