Time to change the gear fluid in the Jeep. I have a dana 30 in the front and 44 in the rear on 37s(I know, I CAN'T BELIEVE YOU'RE RUNNING 37S ON A 30)He's still growing, just don't have the funds for a 4:10s 44 right now and not bumping all that money into a dana 30 for re-gearing. But what does everyone use or think would be best for gear fluid? I always used Mobil 1 in my TJ, but figured I asked.

 

I run Royal Purple, it's really just a matter of opinion as to which is best.

If you have a limited slip (like in a Sahara), and you choose not to run full synthetic, then there is an additive you have to put in to protect the diff.

 

I just run the Walmart brand full synthetic. Someone please correct me if I'm wrong, but from my research all gear oils are fine for the diffs.

 

Any API GL-5 is fine regardless of brand. I choose synthetic for all my fluids. Jeep also recommends higher viscosity in the rear if you tow or have "severe service". I've towed a 5000 pound trailer for over 5000 collective miles. My Jeep still runs like new and has 103,000 miles on it. I've change the diff fluid about 5 times already.

 

 

I used Royal Purple to start, then transitioned to Mobil 1, and Valvoline. The further down the line I get the less need I feel to spend high dollar, mainly cuz I change it so often. That said, still buying a full synthetic. If it was something that was going in for 100k miles, I'd buy the best damn thing I could find, but sometimes I feel fortunate to make it a full 15k interval before cracking the diff open for one reason or another. LOL

 

I'm with resharp001 on this one. I use a Valvoline synthetic, but I also change my diff (and TC) fluids every fall (so around 15K to 20K miles)

 

Agree with both of the above ^, I used to run Mobil 1 synthetic. Now I find myself changing my gear oil after every wheeling trip so I run whoever has the cheapest 75w90 at Advance Auto Parts.

Royal Purple is a waste of money.

 

Rob did you use 75W140 gear oil for towing? It seems that if I do need to use 75W140 oil it only comes in full synthetic. That's not an issue right now. I was thinking of installing another Detroit Tru-Trac in the rear though and the Detroit booklet says don't use synthetic with their Tru-Trac. Just curious. I intend on towing a tear drop trailer with my 2D on 33" tires, with 4.10 gearing.

 

Can't answer on that. I have open diffs. For my needs, the brake lock differential (BLD) that all our jeeps have was enough. I've never come close to being stuck anywhere in sand or snow. So yes, I use the 75-140 in synthetic. I never bothered to see if it was available in conventional. What's the weight on that teardrop trailer?