i did a search but i didn't really put my heart and soul into it. so here i am asking the question.

 

what fluid should i be using in my 87 RX trans and 87 RX LSD rear diff?

 

I'm sure 75w-90 is fine for the trans. but what about the diff? I've only ever changed the fluid on newer subies with viscous centres and viscous rears. Thinking the RX might be a bit different?

 

i have access to a drum of 75w-90 subaru 'extra-s'. The good shtuff...

The LSD takes a special lube. I still have some somewhere. I'll post a PN if I can find it.

 

K0904AA080

 

PN probably obsolete but Anthony's Subaru in BC was able to get it for me about 8 years ago.

Edited January 13, 201016 yr by john in KY

bump from the dead... is this the only thing needed for these diffs? or is it an additive? found it on subarugenuineparts.com for 18 bucks for 1liter using your part number.

It's a clutch type lsd, and most auto parts stores should carry gear oil with the LSD addtive already mixed in or bottles of additive. Doesn't really need a special dealer only mix.

bump from the dead... is this the only thing needed for these diffs? or is it an additive? found it on subarugenuineparts.com for 18 bucks for 1liter using your part number.

 

It is the only thing in my LSD. Filled the diff with it 6 years ago and no problem.

It is the only thing in my LSD. Filled the diff with it 6 years ago and no problem.

 

Sounds like its about time to change it. Even if you haven't put a ton of miles on it, the used fluid can start to do some bad things if just left to sit.

That subaru part number looks to be just a bottle of additive, but I could be wrong.

 

When I recently swapped to RX running gear in my wagon, I used some royal purple gear oil, that already had the LSD additive in it.

 

Redline also makes an excellent standalone additive you can use.

I used the Subaru Extra-S in the trans and Subaru LSD gear oil in the rear and my RX shifts and feels much better.