I want to change my diff fluid which isn't a big deal but I'm just wondering what fluid I should use for the rear? I have a Auburn LSD in there which says not to use a synthetic fluid. So whats best to use thats not synthetic? Would the friction modifier from just a local parts store be fine? I've heard of people using friction modifier from a Ford or GM I can't remember which with this LSD. Should I go the dealer and get one of those or just get what the parts store has?

I'm planning to run Royal Purple 75w-90 in the front. It's what I've always run in the diffs but since I have the Auburn and it says to not run synthetic I need to find something else to use. I was just wondering whats best.

 

75w90 is fine. A heavier fluid is recommended for towing though. Any brand friction modifier is fine. Some fluids already have it added. Check the label.

 

Any ideas on what brand fluid is best thats not synthetic? Seems like most of the good brands are.

 

http://www.partsamerica.com/ProductD...egoryCode=3242

Is that what I want? It doesn't say if it's synthetic. Also what about Lucas? I think thats what the shop put in it now as they said that it wasn't synthetic. Is it really not? Should I get that? What weight fluid should I get? I don't tow a ton but do tow dirtbikes ocasionally.

 

Do they give a reason for not wanting synthetic? If I recall the Auburns have actual friction material on their clutches. Maybe it's too slippery for the clutches.

I think any brand name fluid would be fine. Even the Supertek oils at walmart are pretty decent from what I've read.

 

as hammer i think he has an auburn

 

http://store.summitracing.com/partde...p;autoview=sku


Thats not synthetic is it? I may see if I can find it locally. If not I will get what they have. Should I go to the Ford dealer and get the friction modifier from there or just get it from Advance or Fishers or something? I've read Auburn likes the Ford friction modifier.

Should I go with 80w-90 or 85w-140 or whatever I can find similar to that?

 

140 is recog for late model 3rd gens, when it can go either way they say if you tow etc go with the 140... id go with the 140 regardless..

 

I run the Mopar 75w140 synthetic in my trac-lock but I got it for free. That is factoy fill with the tow package.
I would use any brand FM, I think they are all pretty muchthe same.
can you get a 75 or 85w140 that isn't synthetic? That's a pretty big range for a conventional oil.
Does Auburn make any recommendations?

 

Not that I've seen. I've just seen recommendations for non synthetic oil with Ford or GM friction modifier. The thing I saw had part numbers for those. It said 80w-90 so I guess thats what I shoudl try to get.