Rear diff oil change

roznerd · **Posted:** Mon Sep 24, 2007 6:29 pm

Hey guys - I am going through some maintainance thing with my 02 4X4 KJ and I want to change the rear diff oil. I bought 2qts of Royal Purple Max-Gear and some blue RTV. I read my Hayne's manual, but I want to make sure I don't do anything dumb since the KJ is our main vehicle.

Is 2 qts enough?

Do I need a new gasket or do you just use RTV? Does the RTV have to cure before you can refill and drive?

Thanks in advance

JJsTJ · **Posted:** Mon Sep 24, 2007 6:56 pm

I have always had good luck with the Ultra Copper RTV and no gasket. Let the RTV "set up" for a few minutes and then install the cover. I run in a few bolts finger tight then let it sit for another several minutes then go back and add the rest of the bolts and tighten them up and then fill her up. And yes, 2 Qts should cover it.

roznerd · **Posted:** Mon Sep 24, 2007 7:12 pm

Cool. It's sounds like it shouldn't be a big deal. Do you think I should go get some different RTV? I saw there was some old black RTV around the cover from the 30k checkup and I assume. I just don't want to leak out all my costly oil.

Should I expect to see any metal in the oil?

Thanks for you help.

Tokyojoe · **Posted:** Mon Sep 24, 2007 10:43 pm

You didn't add trac lock to your rear diff did you? It is all open? If so, Continue as planned. If you have the Limited Slip Diff, you need something else. Modifier.

==============

Think V-8 commercial........."Wow! You coulda had Amsoil!"

JJsTJ · **Posted:** Mon Sep 24, 2007 11:33 pm

roznerd wrote:

Cool. It's sounds like it shouldn't be a big deal. Do you think I should go get some different RTV? I saw there was some old black RTV around the cover from the 30k checkup and I assume. I just don't want to leak out all my costly oil.

Should I expect to see any metal in the oil?

Thanks for you help.

You should be fine w/ what you have as long as you coat the cover mating surface well enough. If it is the first cleanimg of the inside of the diff you can expect to see some metal and black gunk on the magnet in the bottom of the diff. Clean it real good, remove the magnet and clean some more. Brake cleaner works well for cleaning it all up.

Jeepjeepster · **Posted:** Tue Sep 25, 2007 12:01 pm

I do not believe you need to add anything for the traclock if you use royal purple. Doesnt it already have the modifier in it?

dkcase · **Posted:** Tue Sep 25, 2007 4:52 pm

I had trouble getting the RTV not to leak, and re-did it twice. At that point I made a gasket.

But that was early and a lot of KJ parts weren't yet listed.

The FelPro rear gasket for the 8.25 diff is an RDS 55047.

If I were going to use RTV I would try "The Right Stuff" from Permatex.

JJsTJ · **Posted:** Thu Sep 27, 2007 9:43 pm

DOH! RP MAX Gear huh? You might want to read this.....
http://www.amsoil.com/products/gearlube ... Paper.aspx

wildrussian · **Posted:** Fri Sep 28, 2007 6:11 am

Its time to go Amsoil. For real!

Pote · **Posted:** Thu Oct 04, 2007 1:12 pm

JJsKJ wrote:

DOH! RP MAX Gear huh? You might want to read this.....
http://www.amsoil.com/products/gearlube ... Paper.aspx

WOW! Royal Purple at the bottom of the heap. thanks for that white paper. Even 2nd place Mobile 1 had almost twice the score tally...impressive stuff that amsoil.!!!!

hooperswish · **Posted:** Thu Oct 04, 2007 1:30 pm

Pote wrote:

JJsKJ wrote:

DOH! RP MAX Gear huh? You might want to read this.....
http://www.amsoil.com/products/gearlube ... Paper.aspx

WOW! Royal Purple at the bottom of the heap. thanks for that white paper. Even 2nd place Mobile 1 had almost twice the score tally...impressive stuff that amsoil.!!!!

Actually, quoting the article, "Mopar and Royal Purple scored well in the 4-Ball EP Weld Test, but failed the Copper Corrosion Test
and GM, with a good 4-ball EP score, foamed badly after oxidation.This would indicate that too much emphasis in one area
of formulation can detract from performance in others.A gear lube is only as good as its weakest link. "

I think rp uses lots of molly which is great for anti foaming and general wear. You will never get anywhere near the stress on rour diffs as tested in the white paper. Don't be afraid of the rp gear oils-they are good stuff.
It all goes back to amsoil's marketing techniques. We all know it is good stuff, but I personally don't like jumping through hoops to get something. (JJ does make it easy though)

Jeepjeepster · **Posted:** Thu Oct 04, 2007 7:45 pm

Looks like I did good on the castrol then. Paid $60 for a 5 gallon bucket of 75w-140 SYN.

JJsTJ · **Posted:** Thu Oct 04, 2007 10:15 pm

Jeepjeepster wrote:

Looks like I did good on the castrol then. Paid $60 for a 5 gallon bucket of 75w-140 SYN.

$60 for their Syn gear lube?! :shock:

$3 a QT?! Heck, I honestly would have bought that too for that cheap. I can't even get dino gear lube in 75W140 for that cheap. (not that I would run it)

Dutchy · **Posted:** Fri Oct 05, 2007 6:00 am

I used RedLine, if it is good enough for a jet engine it is good enough for my KJ>

JJsTJ · **Posted:** Fri Oct 05, 2007 10:36 am

Dutchy wrote:

I used RedLine, if it is good enough for a jet engine it is good enough for my KJ>

The oil they make for a jet engine is nothing like what they make for an auto. Please don't think you are getting the same thing.

Dutchy · **Posted:** Fri Oct 05, 2007 10:48 am

JJsKJ wrote:

Dutchy wrote:

I used RedLine, if it is good enough for a jet engine it is good enough for my KJ>

The oil they make for a jet engine is nothing like what they make for an auto. Please don't think you are getting the same thing.

Eh...Yes!

The grade I used can also be used for jet engines, it says so on the bottle.

Great stuff, fixed my 40.000 Miles ongoing rear diff problems in a second and the ltd slip still works great when you need it, great stuff!

Next oil change will be RedLine synthetic for my CRD, that's for sure!

roznerd · **Posted:** Fri Oct 05, 2007 8:07 pm

Hey guys. I did the rear diff oil change last night.

Pretty easy. Cleaned off two different colors of RTV. Some very fine metallic particulate was in there ,but that was it.

Loaded it up with blue RTV and put it together to cure for 1 hour ( while I dropped the D-line to grease splines), then filled it up.

No leaks. 2qts of Royal Purple did it. That's probably the one and only time I will need to do that job.

Thanks for all the guidance and help. - Brian

snowsport · **Joined:** Tue Oct 18, 2005 11:52 pm **Posts:** 1211

Fun, isn't it? I did mine for the first time some months back. Feels like you accomplished something. What's your next service challenge?

roznerd · **Posted:** Tue Oct 09, 2007 4:58 pm

Yeah, I will probably do the front struts next ( stock height), and put synthetic in the T-case, motor, and front diff. I'm not looking to modify anything, just keep my KJ nice and reliable.

hooperswish · **Posted:** Wed Oct 10, 2007 9:11 am

roznerd wrote:

Hey guys. I did the rear diff oil change last night.

Pretty easy. Cleaned off two different colors of RTV. Some very fine metallic particulate was in there ,but that was it.

Loaded it up with blue RTV and put it together to cure for 1 hour ( while I dropped the D-line to grease splines), then filled it up.

No leaks. 2qts of Royal Purple did it. That's probably the one and only time I will need to do that job.

Thanks for all the guidance and help. - Brian

I think your "cure for one hour" was the secret of your success. I think people run into leaks when they simply crank the bolts up tight right away. Congrats... it sure is fun to do simple maintenance that makes a positive difference...

Rear diff oil change

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