Diff oil

[skinnyguy]

I’m about to do a diff. Service, I run stock wheels and tires on my rubicon 4 months of winter and run 35” NITTO trail grapplers on black rhino arsenal wheels the other 8 months. Should I upgrade my gear oil to the 75w140 or is the 75w85 ok? I don’t off road excessively or tow. Thanks

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[Biggy]

If your not towing i would stick with the 75w85.

 

[jac04]

You can also use 75W90, which is usually more readily available.

There has been quite a bit of discussion about using 75W140. Here is some good reading:
https://www.jeepgladiatorforum.com/...ial-fluid-for-towing-rubicon-50-towing.86137/

 

[Hootbro]

75W-90 is my vote unless you are towing.

 

[ericw.]

I run this. It's probably overkill but I tow and don't mind spending more on it.

 

[nanook12]

What weight is that redline? I picked up a bunch of quarts of synthetic 75W-90 last year. The stuff was almost the same price as the dino oil! I’m in the cold country and need the lower poor point of the synthetic.

 

[nanook12]

 

[bleda2002]

I run 75w140 but I am regeared and tow heavy in Florida heat. The guy that did my gears only warranties it with 75w140 so that's what I went with.

I will say that I run RP gear oil and I just changed it after probably 8k summer miles towing 4700lb camper, and 40k miles on beadlocks 39s/38s and that royal purple gear oil still looked brand new, still purple no burn smell, really impressed with it honestly.

 

[ericw.]

What weight is that redline? I picked up a bunch of quarts of synthetic 75W-90 last year. The stuff was almost the same price as the dino oil! I’m in the cold country and need the lower poor point of the synthetic.

It says this on their website:

• Film thickness greater than an SAE 75W250, yet low fluid friction like 75W90

but with it being thicker, I would probably avoid it in super cold environments.

 

[froril]

The synthetic Valvoline in the bag so much easier to deal with than the old plastic bottles. I have ARB lockers and per their recommendation I’m running 75w140 but if I was stock probably just run 75w90 and if I had the limited slip use the Mopar additive.

 

[jac04]

I have ARB lockers and per their recommendation I’m running 75w140 ...

Interesting. I wonder what about the ARB lockers makes them recommend 75W140. It is usually the bearings & gears that dictate the recommended fluid.

 

[froril]

Interesting. I wonder what about the ARB lockers makes them recommend 75W140. It is usually the bearings & gears that dictate the recommended fluid.

No idea.
Probably because it’s hot in Australia.

FWIW the backlash on both front and rear gears were out of spec “loose” by a few thousands from the factory… I reset up the gears to get it into spec with my factory ring and pinions. So I’m unsure of how much the gear lube spec really matters if the gears aren’t set up right from the factory.

At this point if the stock gears turn into jeep glitter and chunks from the 75w140 I’ll just re-gear it.

Actually here are the specs. I took a stab in the middle of the Temperate spec

 

[Hootbro]

FWIW the backlash on both front and rear gears were out of spec “loose” by a few thousands from the factory… I reset up the gears to get it into spec with my factory ring and pinions. So I’m unsure of how much the gear lube spec really matters if the gears aren’t set up right from the factory.

Just wondering, how many miles did you have on it when you checked the backlash? My understanding is the backlash spec is for setup of new gears and used gears over time will loosen up the backlash.

 

[nanook12]

The temp range on your gear oil chart is only good down to temperate range.

 

[froril]

Just wondering, how many miles did you have on it when you checked the backlash? My understanding is the backlash spec is for setup of new gears and used gears over time will loosen up the backlash.

Around 5k miles on the rear. Way less than that on the front. Wear in is totally plausible though.

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