For my transmission:

I put in Swepco 201 (80W-90). It is a dino fluid that has climbing abilities. When it is cold out the shifting can be very difficult and baulky. What I mean is, shifting from 1-2nd gear is difficult unless you match the shift properly. It will lock you out of second unless the shifting timing is correct. Even though it locks the gear out, it will not allow it to grind. I got used to it since I rarely use the synchros to shift. Once the oil is warmed up the feel of it is amazing. The metallic feeling when shifting is gone. You can "feel" the fluid smoothing out the action. I love this fluid once it is warmed up. It is also dark blue in color and is GL-5 rated (to keep the hypoid gear in the tranny happy).

For the rear diff:

I just filled it with Quaker State 75W-90 Synthetic gear oil (GL-5). I'm not too worried about the diff since it is very easy to change the oil out. Just make sure you change the oil out waaaay before the service recommendation. The oil that came out when I changed it at 15,000 miles was dark and dirty. The plug was also covered with a good amount of black "dirt". After I changed the oil out, I noticed that the noise from the rear end decreased dramatically.

For my engine:

I use Mobil 1 0W-40 (European Car Formula). This oil contains some moly, is rated A3, and is also approved for extended drain intervals. The reason for this oil is that the start-up noise (cold engine) is gone. When I tried thinner oils, the engine would sound like it is falling apart when it is cold out. I am not a fan of very thin motor oils, especially with the EJ25 engine.

Power Steering fluid:

I noticed that is was a bit underfilled from the factory. So I bought a bottle of Lubegard Red (Transmission additive) and topped off the power steering with the Lubegard. I will eventually change it over to Mobil 1 Full Synthetic ATF.

Sorry for the long post.

Jay

 

Who moved this thread to transmission? There is a lot more information here than just tranny stuff...

In any case, I just took my 02 WRX in for the dealer-mandated 30k service and they used all factory fluids for the transmission and differentials, or so they claimed. How long should I wait before swapping them out for synthetics, or should I just run on the factory stuff for now? The car isn't tracked, but it does experience 110-degree heat for 4 to 6 months a year.

 

Not sure how this got here- I thought I had it in the Maintenance forum.

 

Oh, now I see- I must have copied it to Transmission some time ago. Not sure why. I'm going to close this thread and leave it. There's a sticky of this same info in the Maintenance forum.