Gear Oil & 12 Bolt
 

What kinda gear oil are you guys running in your 12 bolts? I have always used non synthetic in my stock rear cause I know that's what your supposed to run with the stock diff's etc. But the 12 bolt will be here this week and Im running a full spool now so Im wondering if synthetic will be a better idea. Also there is no need to run limited slip additive anymore I presume.

With a spool I would run synthetic.

Agree.

Rich Krause

The synthetic oil is better than conventional... if you have a spool, then I too agree to run synthetic.

I use 75W90 synthetic in all my diffs.

Beautiful, I will run that mobil 1 75w-90 synthetic then :)

thanks guys :thumb:

I am the odd ball ;) I run Kendall 85-140 to keep shock loads in check ;) It is over kill but I do have to drive 100 miles to race and then home again.

A thin Synthetic should be fine as the other guys said.

All the new highway trucks use 75w90 synthetic in the diffs. Pulling 60,000 pounds through 18 gears is a lot of stress on the diff. They've also extended the oil change requirement with the synthetic to 500,000 miles. Mineral oil was only 120,000 miles. That's saying a lot for the synthetic oil.

Yea I was talking with moser today and they were saying to run non-syn :irk: I told them even without a diff and he said YES because that's what the gear company tells them to run :confused: Im sure it's prolly just some tech guy that reads something off paper and prolly has no shop experience so oh well..

Does anyone know how much gear oil the 12 bolt takes?

I'll say it once more: run dino juice (non-synth) in your diff if you have a friction/clutch type posi and also use friction modifier. AFAIK all of the posi's are designed for regular (non-synth) lubricants.

Rich Krause

LOL I don't have a posi rich :) Thats what this whole thread is about :)

DOH! Well then, run synth!

Rich

You really think so eh? I know that moser is supposed to give us their "OFFICIAL" point on things and they SWEAR by running NON SYN cause they say it stays on the gears longer etc. Sounds like a VALID point. I know that SYN is prolly better for performance since it's slippier and doesn't cause as much drag on things but Im not too concerned with that. I just want to use what will be best for STRENGTH and LONGEVITY.

Same here.

They say that because that is what the gears are cut for. The new gears in the truck you are talking about are cut in a different way and even setup different in many cases.

They may also Void any Warranty you have if you run Synthetic....then again Moser offers NO warranty on the damn thing So run the synthetic ;)