Diff Oil

I checked my diff oil (front, dipstick accessible from engine bay) the other day and it was only right above the low mark. should I add some or just change it? if I should have to change it, how much does it take, how hard is it to change and should I use OEM Subaru diff oil? and also should I do the rear at the same time?

Just did mine, very easy. use this thread. http://legacygt.com/forums/showthread.php/pictoral-guide-changing-transmission-and-rear-diff-fluids-5mt-05-94834.html

It's pretty easy and cheap to change the front differential fluid, I would just change it. There are many different fluids you can use as long as it's GL-5 rated, and I would probably just stick to 75w-90 even though the FSM says you can run other straight weights.

 

I've run the following fluids which you could try too, even though things are slightly different for me since my manual transmission shares the diff fluid, whereas your diff gear oil is separate from your 5EAT fluid.

Walmart supertech synthetic blend 75w-90 gear oil, around $5/qt

Amsoil severe gear 75w-90, around $14/qt I think I paid?

Subaru Extra-S 75w-90, around $12/qt

Red Line 75w-90NS (NS for MT purposes), around $15/qt

 

The only other advice I can give is that since your front diff holds 1.4qt-1.6qt's of fluid, I would probably start off filling with around 1-1.2 quarts, checking the level, and adding if needed. My 5MT holds 3.7qt's, and I generally hit the full mark with around 3.3qt's of fluid. It's easier to add more fluid than it is to remove too much fluid.

 

I usually let subaru change my rear diff fluid for around $40.

For fluid I recommend subaru extra s in both the trans and diff.

that write up is awesome! but I have the 5EAT and have separate dipsticks for diff oil and tranny fluid, is there two separate drain plugs then? a very noobish question I'm assuming but I've never had to do this stuff.

Yes, two separate drain plugs. I've attached a picture of the front differential drain plug location, and the ATF drain plug location to see the difference.

thank you! makes my life so much easier. I appreciate the help a lot.