Do the D-44's under a Rubi need any additives or modifiers? Can't find anything listed anywhere.

No! Just plain old 90 wt or 80-120. According to the service manual.

Synthetic is good, or just change it once in a while - especially if you go swimming with it.

Humm... does you Rubicon's rear axle unit have an air-actuated locking diff, or is it a plane Jane unlocked diff?

Not my Rubi, but we are changing the fluid now (it's getting new heavy duty covers). It has the standard Rubicon D-44 with the air actuated locker.

Electronic Leve, my Sister just got one, wheeeled in last weeekend up kinda near you. Does real well, the dash lights showing front and rear locked are cool.

If you've got the locker:
<ul type="square">[*]4 quarts of 90weight gear lube and[*]Two bottles of friction modifier[/list]

Not according to the service manual. Just straight 90 wt oil.
And not according to the Jeep dealer parts guy, no addative listed for the Rubi lockers.
Trac-Loc limited slip yes, needs the friction modifiers.

And not according to a friend that's the dealers "Diff guy."
Friction modifiers will cause undue wear on the air locker.

The Rubicon diffs - both of them, are low pressure air lockers. They "kick in" about 8-10 lbs.
They are NOT ARB's, not electrically actuated - unless you count running the compressors with electricity.

The small compressors - 2, one for each diff - are mounted on the belly pan - top rear edge, left side.
I moved mine up under the hood out of harm's way - left side, in front of the brake booster. They don't like water!!! When they get damaged by rocks or water, replacements are more than $260 EACH!

There is an electrical sensor on each diff as well - giving the impression it's electric - look close - see the airline to the compressors? There's also a vent hose up going up next to the radiator (front).
The sensor switch detects two things - the "command" to engage (air is applied, the ring has moved a little, trying to engage but the dogs haven't lined up yet, not fully seated - that flashes the dash light.

When it fully engages, the light stays on steady. The signal from the sensor switch is sent to the computer, it operates the dash light.

Don't apply much power when the light's flashing - it's not fully engaged, that will damage it.

The computer normally prevents - or unlocks the lockers - from engaging at speeds over 10 MPH. Not good if you are storming a sand hill. But it's a safety thing - you don't want a passenger to say "what's this" and engage them at 70 MPH.

There is a website that shows how to bypass that function easily so they'll stay on above 10. With a safety switch to prevent the above.

But still you aren't totally in control. You have to engage the rear before the front. Sometimes you want front only.

The best way - run 12 volts through a couple of switches to each compressor, taking the computer out of the loop. The sensor lights will still be funcional as it's a separate circuit. Then you have full control. It won't set a code.

Rumors:
Limited slip when the lockers are off - NO

Electronic - kinda, electricity runs the compressors.

4 Lo only, NO!

Indestructable --- NO NO NO!!

Cheap --- NO - the locker section alone is about $2500 - center only, no R&P. But an entire new, complete, assembled Rubi axle (rear) - disc to disc including the locker is only about $2000. Go figure.

I have a center section on my bench right now. Looks fine, but it's dead inside. Goes "crunch crunch" then locks up even when not engaged - on the street. He had to trailer it back from Moab. Gotta take it apart to see what died.

cut and paste...

DESCRIPTION - AXLE LUBRICATION
NOTE: DiamlerChrysler recommends using Mopar® lubricants or lubricants of equal quality.

FRONT AXLE
181 FBI (Model 30) - Mopar® Gear Lubricant 80W-90 (Trailer Towing Mopar® Synthetic Gear Lubricant 75W-140)
216 FBI (Model 44) - Mopar® Gear Lubricant 80W-90 (Trailer Towing Mopar® Synthetic Gear Lubricant 75W-140)
RUBICON 216 FBI (Model 44) - Mopar® Synthetic Gear Lubricant 75W-140
REAR AXLE
194 RBI (Model 35) - Mopar® Gear Lubricant 80W-90 (Trailer Towing Mopar® Synthetic Gear Lubricant 75W-140)
194 RBI (Model 35) 4.56 Ratio - 2.4 L Enigne and 42 RLE Automatic Transmission - Mopar® Synthetic Gear Lubricant 75W-140
226 RBI (Model 44) - Mopar® Gear Lubricant 80W-90 (Trailer Towing Mopar® Synthetic Gear Lubricant 75W-140)
RUBICON 226 RBI (Model 44) - Mopar® Synthetic Gear Lubricant 75W-140
NOTE: Trac-lok® equipped axles require 118 ml (4 ounces) of Limited Slip Additive in the lubricant.

[ QUOTE ]
RUBICON 226 RBI (Model 44) - Mopar® Synthetic Gear Lubricant 75W-140
NOTE: Trac-lok® equipped axles require 118 ml (4 ounces) of Limited Slip Additive in the lubricant.


[/ QUOTE ]

This is the part I don't get. I don't know of a Rubi that came with the Trac-lok. I thought ALL Rubicons came with the Air actuated lockers, which has far as I can tell is different from the Trac-loc.

I think that "NOTE" applies to the entire category, and not just the Ruby part.
Isn't the friction modifier ONLY for the LSD? I thought it had something to do with the way the clutch packs worked. I don't claim to understand it completely, but since they rely on friction within a clutch pack they require a different lubricity (is that a word?) than a geared system, such as a normal locker.