Transmission Fluid

[HelluvaEngineer]

Hi Guys,

I am not an expert with this, I just wanted to pass on some experiences a lot of the Subaru guys have had.

There has been many discussions about the best transmission fluid for the Subaru tranny on different Subaru Forums. But there has been a general consensus (With some disagreeing) that the EXTRA S fluid from Subaru gives the best shifting transmission. I personally noticed a distinct improvement when I switched to in on my Legacy GT.

edit: Forgot to mention that I have a C3 Corvette with a Richmond 5 speed and It also shifted better with the EXTRA S fluid.

[metalmaker12]

Motul or extra s

[Slatt]

I reckon the first determining factor will be what is recommended for the limited-slip or torque-biasing differential you install. If I recall right the TBDs don't much care, a clutch-type LSD like the Cusco's do care (Motul Gear 300). Sorry to be vague, I hope someone else will confirm.

[HelluvaEngineer]

I reckon the first determining factor will be what is recommended for the limited-slip or torque-biasing differential you install. If I recall right the TBDs don't much care, a clutch-type LSD like the Cusco's do care (Motul 600?). Sorry to be vague, I hope someone else will confirm.

I believe there are additives you add if it is a clutch style. But I thought there were not any clutch style ones for the front? (818 rear) But I have not looked into it very much.

There are threads on the legactygt.com website where people have tried different fluids and most end up back with the extra S. There is one thread that is something like "EXTRA S is da bomb" or something like that.

[Slatt]

RalliSpec has them. Cusco RS for 5MT.

Lube selection for a clutch type inside a gearbox involves some compromise of LSD performance and synchro life / performance.