Questions about changing the rear differential gear oil

kissfan79 · **Posted:** Mon Feb 27, 2012 4:14 pm

Hey guys....
I'm getting ready to change the gear oil in my rear differential and have a couple of questions. First off.....I have read that none of the 06 CRD's have a trak-lok rear end and don't need the friction modifier. Is this true or should I confirm the abscence of a trak-lok rear end to be safe?

Second....I know the manual states that I should use a synthetic 75w-140 (I do tow some trailers) but it seems there has been some debate as to which type is best....dino or synthetic. Which do ya'll reccommend?

Lastly....is it best to jack up the Jeep to do the job? I read somewhere that jacking it up was necessary to get the right angle on the differential (letting it hang down a bit) and filling it to the fill hole to create the proper fill when let down. Correct or am I better off just filling with a set amount of gear oil?

Thanks again for everyone's help and knowledge.

Jim

Doolop · **Posted:** Mon Feb 27, 2012 7:29 pm

The quick and simple answer to your friction modifier question is to call your local stealership and provide your VIN.

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tjkj2002 · **Posted:** Mon Feb 27, 2012 8:06 pm

No trashloc in any '06 or '07 KJ's due to ESP.

Pour in 85w-140 dino gear oil and your diff you love you long time.

CRDMiller · **Posted:** Mon Feb 27, 2012 8:15 pm

Typically to drain the differential you remove the differential cover.

This is necessary in order to clean the mating surfaces and ensure the sealing of the cover to the housing by use of a gasket or sealant such as rtv.

While the cover is off you may examine the differential carrier. If for some reason you had a traction control device or limited slip differential it would be obvious by the existence of clutches.

The presence of clutches would demand the use of a lubricant that was rated for use with a LSD and or supplemented by an additive for said lsd.

But you exclaim, I want to have the correct additive on hand before I take it apart!
A wise precaution.

Turn off esp and attempt several burnouts with the transfer case in 2wd. If you leave two strips of rubber on the pavement you have a traction control device.

You could also indiscriminately add the additive with no ill effect.

It is easy to take actions based on preconceived notions and assumptions

Joe Romas · **Posted:** Tue Feb 28, 2012 9:05 am

Like tjkj2002 said above :banghead:

NO TRACK LOCK IN 2006 BECAUSE OF ESP :dizzy:

Also since there's no drain plug the cover MUST be removed to drain the oil :JEEPIN:

kissfan79 · **Posted:** Tue Feb 28, 2012 12:42 pm

Thanks for the replies guys.....so no problems using the dino oil even though the manual states synthetic of a slightly different weight? Does anyone know the exact fill capacity of the differential to bring it to the correct level? It seems more logical to go that route vs trying to guess at getting it 1 cm below the fill hole.

Jim

ChesterCRD · **Posted:** Tue Feb 28, 2012 12:47 pm

I fill it until it runs out and then insert the plug. I figure if it's overfilled it will work its way past the rubber plug (not a tight seal).

kissfan79 · **Posted:** Tue Feb 28, 2012 1:00 pm

That bit of overfill won't cause any problems before it seeps out? Also....do you jack the back end up or just do the job with it sitting on the pavement?

Jim

ChesterCRD · **Posted:** Tue Feb 28, 2012 2:35 pm

I've never had a problem with the little extra in there. I haven't seen any leak out either.

I set the vehicle on jack stands so the axle hangs down. This makes it easier to access the bolts in the top of the cover and gives a better angle for pouring in the new oil (these days I use a hand pump instead of pouring usually).

My process is like this:

1. Put vehicle on jackstands so the axle hangs down.
2. Remove the differential cover.
3. Remove rtv from the differental and cover. Clean rtv surfaces with wd-40, followed by brake cleaner. (after waiting long enough so no more oil is running out of the diff)
4. Inspect cover and diff for any problems.
5. Apply rtv to differential, go around bolt holes.
6. Put cover on, finger tighten bolts. Let it sit for an hour for rtv to cure. (check rtv instructions for time...may be longer or shorter depending on what you get)
7. Give each bolt 1/2 to 3/4 turn with a wrench.
8. Add gear oil of choice until it runs out fill hole.
9. Wipe off any oil that spilled out.
10. Insert plug.
11. Clean off diff cover with wd-40.
12. Drive as normal, check for leaks and level (remove plug, feel with finger) after 24 hrs.

kissfan79 · **Posted:** Tue Feb 28, 2012 2:46 pm

Cool...thanks. When you say go around the bolt holes with the RTV.....should the bolt holes be on the "inside" of the RTV or the "outside" of the RTV. BTW...what part of Florida are you in? I was just in Tampa for the state fair.

Jim

ChesterCRD · **Posted:** Tue Feb 28, 2012 2:55 pm

I mean surround the bolt holes with RTV. It helps provide a good seal and allows the bolt to put more even pressure on the pan so it doesn't deform around the bolt holes.

I'm in Palm Bay, just south of Melbourne on the east coast. Where are you? There are a few of us Floridians dieseling around.

kissfan79 · **Posted:** Tue Feb 28, 2012 3:04 pm

Gotcha.....thanks. Actually I'm from North Carolina. My wife and I were in Tampa as a vendor at the State Fair. It was great....we enjoyed our time there.

Jim

Radman · **Posted:** Tue Feb 28, 2012 3:14 pm

I pump mine out with an oil extractor type pump. No need to remove cover or replace the sealant etc. Note that the oil is thick so try to remove it when the transfer case is warm it will be easier to pump.

Questions about changing the rear differential gear oil

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