[Ruskin]

I know nothing about gear oil, so I'm looking for some general help about what to put in the front and rear diff. (yes, I've searched and read). Everyone has a preference about what's best, so please just let me know if I'm about to screw this up.

I have an 07 X Unlimited with 4.10 gears.

For the front bought AMSoil Synthetic Gear Lube SAE 75w90.

For the rear limited slip D44 bought Severe Gear SAE 75w140.

Both oils are synthetic. I did not get any additives.

Does this sound right?

Thanks.

 

[PhilD]

Sounds good to me.

For various reasons I've changed my diff fluids way too many times, but here's what I've ended up using.

I run cheap 80W90 in the front, it barely gets any wear and looks as good as new all the time. I did run Royal Purple 75W90, but it leaked out passed the axles seals.

I started with Royal Purple in the rear also, but after draining it a few times, I switched to cheap 80W90. My rear diff gets very hot, so I've just switched to Mobil 1 75W140.

 

[MichaelW]

I'm running the same. the 75-140 is recommended for towing. I am running additive in back as well, helps with disengaging the locker faster/smoother.

 

[Ruskin]

Thanks for the info. I changed both diffs yesterday at 10,500miles.

The front D30 oil was rather milky and you could see metal particles in the oil (very very fine dust like particle I assume from break-in).

The rear D44 oil was very dark, again with metal dust size particles. The suprising thing was the amount of junk on the drain plug manginet...about a 1/4 inch of stuff (is this normal?).

So, two lessons learned by the nubie:
1) The D44 Diff oil is easier to change than the engine oil because of the drain plug (wish the D30 had one)
2) There is junk in there after only 10K miles.

Now that I've done this, how big of a difference does this really make? General maintenance is good, but what if you never changed your diff oil, or only changed it every 50K miles? Those of you with more experiece have any insight or stories?

 

[BaltChief]

Thanks for the info. I changed both diffs yesterday at 10,500miles.

The front D30 oil was rather milky and you could see metal particles in the oil (very very fine dust like particle I assume from break-in).

The rear D44 oil was very dark, again with metal dust size particles. The suprising thing was the amount of junk on the drain plug manginet...about a 1/4 inch of stuff (is this normal?).

So, two lessons learned by the nubie:
1) The D44 Diff oil is easier to change than the engine oil because of the drain plug (wish the D30 had one)
2) There is junk in there after only 10K miles.

Now that I've done this, how big of a difference does this really make? General maintenance is good, but what if you never changed your diff oil, or only changed it every 50K miles? Those of you with more experiece have any insight or stories?

That "Junk" on your drain plug is metal shavings. The drain plugs are magnetic and designed to collect the shavings. The milky front concerns me, normaly milky fluid means water got in. Did you run through Mud or strams? Is your vacum tube on good? I would check if I were you.

 

[Ruskin]

That "Junk" on your drain plug is metal shavings. The drain plugs are magnetic and designed to collect the shavings. The milky front concerns me, normaly milky fluid means water got in. Did you run through Mud or strams? Is your vacum tube on good? I would check if I were you.

Ya, Jeep took a huge bath. Breathers are on good and so are the fancy values at the end of the breathing tube, but they were submerged for 1-2 seconds.

 

[PhilD]

Ya, Jeep took a huge bath. Breathers are on good and so are the fancy values at the end of the breathing tube, but they were submerged for 1-2 seconds.

Still will suck in water, as the diff cools because it is submerged, it sucks in air through the vent, the little caps do not seem to keep water out well, I've sucked in water a couple of times.

 

[W3CSX]

One other consideration when changing your diffs. Even though both the fill and drain plugs look the same. Only the drain plug is magnetic. If you switched them inadvertently while they where out. Any loose shavings will not adhere to the plug staying suspended in the oil. This can / will lead to premature wear.

Since you have already refilled. You can just take out the fill plug and just see if it magnetically sticks to the diff cover. If it doesn’t your fine. If so...
Maybe that second change will come sooner than you thought.

 

[Bigjerm]

So, two lessons learned by the nubie:
1) The D44 Diff oil is easier to change than the engine oil because of the drain plug (wish the D30 had one)
2) There is junk in there after only 10K miles.

my D30 has a drain plug and fill plug. Might want to look it over again. I changed mine about 4k miles ago