Confused on what gear oil and weight to use on Dana 30 with ARB locker

Lifted straight six

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So i’m having a little trouble, I haven’t done any work on my dana 30 with the ARB cover and locker, and I don’t know the exact fluid to use, ive heard 75W-90, 75W-140 and 85W-140... That’s a huge range. Also am not sure what the proper fluid capacity is in a Dana 30 with an ARB locker and cover, can anyone help me with this?
 
Fluid should be just above the bottom of the axle tube. While your there inspect your cover for impact marks from your track bar. It is common to have contact with the oversized ARB diff covers.
 
My trac bar clears it perfectly, I haven’t had the problem that some have had, but I also have currie everything upfront, How will I know it’s above the axle tube if I have an ARB cover with the full hole on top, I don’t have a hole for it to come out of
Fluid should be just above the bottom of the axle tube. While your there inspect your cover for impact marks from your track bar. It is common to have contact with the oversized ARB diff covers
 
My trac bar clears it perfectly, I haven’t had the problem that some have had, but I also have currie everything upfront, How will I know it’s above the axle tube if I have an ARB cover with the full hole on top, I don’t have a hole for it to come out of
isn't there a dip stick/magnet attached to the fill hole cap? You should be able to determine exactly where the level is with that. I put in the factory recommended 1.25 quarts in the 30 with the same setup you have, if memory serves the first time I did that I checked it against the dipstick & it was all good
 
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Any of those viscosities would work for you, they're actually very close to each other. Gear lube viscosities are measured on a different scale than engine oils are. For the differential I'd go for a conventional GL-5 gear lube, your gears will run cooler with that than with a synthetic. Really.
Thank you for the knowledge Jerry, have been reading your posts since I started my first jeep tj build about 7 years ago!
 
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I haven’t had the problem that everyone has been talking about with that, Fully flexed, sway bars connected or disconnected it doesnt matter I still have about 3 1/2 inches between track bar and diff
None of those scenarios you listed are typically where the track bar diff cover interference issue presents itself.
 
None of those scenarios you listed are typically where the track bar diff cover interference issue presents itself.
Nope. It’s only apparent with both sides stuffed at the same time. Like going through a big dip or such. I have been known to drive a bit too fast on the mountain dirt roads. Having any contact there was not a chance I was willing to take. Contact between the diff cover and track bar can break a track bar or mount leaving you without any steering control. Bad, bad juju.
 
And for your ARB locker, I'd run the 85-140 non-synthetic if you plan on wheeling a lot or towing anything.
 
I'll have the same setup as this.
Using 85w-140 non-synthetic, do you still need the friction modifier? Same question for the Dana 44 rear. (04 LJ)
 
I'll have the same setup as this.
Using 85w-140 non-synthetic, do you still need the friction modifier? Same question for the Dana 44 rear. (04 LJ)
I'll have the same setup as this.
Using 85w-140 non-synthetic, do you still need the friction modifier? Same question for the Dana 44 rear. (04 LJ)
i did not use any friction modifier