[Project_STI]

We called several dealerships and have gotten conflicting information. Since we are in need of information fast, we have contacted another source and thought we should come here to receive information sooner.

Basically, we are change the diff and tranny oils to synethic.

Since we have a suretrac limited front differential and a mechanical limited slip rear differential, what do the manuals say to put into the diffs?

What do the manuals say for the tranny?

So far, here are some answers we have gotten from dealerships and those considered Rally experts:

Front & Tranny- NS gear oil
Rear - gear oil with limited slip factor


Front & Tranny - manual transmission oil
Rear - NS gear oil

Front & Rear - gear oil with limited slip factor
Tranny- NS gear oil

While we are leaning to go with what the rally experts have said, we still want to know we are going against what Subaru recommends if that is the case.

If you have the STI manuals downloaded from the Subaru website with this information, please email them to projectsti@yahoo.com, and post the information here. This will be useful to everyone as they decide to change their oils.

Thank you for all your input.

[Slowride]

From the service manual:

Page 6MT-30, Transmission:

Use GL-5 or equivalent

Page RM-3, Recommended Materials:

Manual transmission oil: GL-5
Rear differential gear oil: GL-5 (For mechanical LSD)

Page RM-4 specifies the viscosities vs. operating temperature ranges: 90W for 32 degrees C and above, 85W for -22 C and above, 80W for 86 C and below, and 75W-90 for all temperatures.

I can't find any reference to lube for the front differential--maybe it shares the tranny oil.

[Antimullet]

I'd stick with regular gl5 or higher dinosaur oil for the tranny or redline MT-90, otherwise, synthetic oils can actually cause synchros to grind (due to lack of some friction that they require) like what happens in the WRX.