HOW TO: Change your front/rear diff oils

Discussion in 'How To' started by jeepkj02, May 6, 2006.

  1. Outofideas

    Outofideas Full Access Member

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    I just changed the fluids on mine and it was easy. Luckily I work at a shop so I was able to use a lift after my techs were done for the day. I used 74w140 royal purple both front and rear so I'll see how good it performs for the $$. I used a quick curing rtv that is usable in 5 minutes so i did not have to wait on the rear to fill and no leaks so far. When removing the diff cover on the rear, I leave the top bolt in just a few threads when i pry the cover loose so it does not pop free and make a huge mess. When most of the fluid is drained take out the last bolt and then pull the cover free.


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  2. sevenhelmet

    sevenhelmet Full Access Member

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    I just read the dino/synthetic gear oil thread. Yikes. I think I'm going to just buy dino oil for both diffs now. It's cheaper than the synthetic stuff anyway.
     
  3. sevenhelmet

    sevenhelmet Full Access Member

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    I just picked up a gallon jug of Coastal 80W-90 "dino oil" for a steal. I'll use some of that for the rear axle, and put my leftover 75W-140 synthetic oil in the front axle.

    Unless it's cool to use the remaining 80W-90 in the front diff as well... any experts care to weigh in?

    If not, I'll play it safe- my Jeep's health isn't worth the risk!

    @ Outofideas: Be interesting to hear about how the RP gear oil works for you. I use RP Synchromax in my transmission, and she shifts oh-so-smooth. I used Pennzoil Synchromesh once- NEVER AGAIN.
     
    Last edited: Jan 4, 2012
  4. first&lastKJ

    first&lastKJ Full Access Member

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    Now i'm confused on what gear lube to use.
    The owners manual for our 07 says
    Front 80w-90
    Rear 75w-90 synthetic. For towing use 75w-140 synthetic.
    Our 02 owners manual says use gear lubricant, for towing use 75w-140 synthetic and thats it.
    Neither have been changed since new. Does it really matter what weight I use?
     
  5. tjkj2002

    tjkj2002 Full Access Member

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    If you don't tow or offroad it 80w-90 dino front and rear is great.If you tow or offroad 85w-140 dino is your choice then.
     
  6. first&lastKJ

    first&lastKJ Full Access Member

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    What is "Dino" never heard of it until this post, is it synthetic, who sells it?
    Yes I tow, so 85w-140 front and rear or just rear only?
     
  7. speedracerbubba

    speedracerbubba Full Access Member

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    Dino is just another way of saying conventional oil rather than synthetic.

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  8. tjkj2002

    tjkj2002 Full Access Member

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    Or another way to say it is..............

    $5 per qt compared to $18 per qt.
     
  9. theroofable

    theroofable Full Access Member

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    I am having a hard time finding some dino 75w-140 or 90 gear oil. Anyone have a good place to get it, I tried online searching for it at napa and walmart but they only carry synthetic, or so it seems.
     
  10. tjkj2002

    tjkj2002 Full Access Member

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    75w-90 and 75w-140 are synthetic weights.Dino weights are 80w-90 and 85w-140.
     
  11. theroofable

    theroofable Full Access Member

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    Oh ok, so what I should be looking for is the 85w-140 since it holds up better. Thank you sir. Now would it be better to add the 85w-140 to the rear even if I dont do regular offroading/towing. I only do that once every few weeks, but would like to put it in anyway. HERE is some I found. Good enough? Also, do you bolt the cover back on and then wait 30mns with the rtv or wait 30mns before putting them back together.
     
    Last edited: Jan 6, 2012
  12. tjkj2002

    tjkj2002 Full Access Member

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    It's really your choice,but when you tow if you tow close to max weight 85w-140 would be my choice.

    The way I do my diff covers is.........

    After cleaning both surfaces,apply bead of RTV on diff cover(around all bolt holes),let sit for about 5-10 mins.Then put diff cover on and tighten bolts till you just start to see the RTV ooze out the sides.Let sit for another 5-10mins then finally fully tighten all cover bolts.Let stand for another 15-20mins and refill.Never had a cover leak from doing it the way I just listed.
     
  13. TwoBobsKJ

    TwoBobsKJ Full Access Member

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    I've always done the diff cover/RTV the way Troy describes. And like Troy I've never had a leak.

    As far as the oil, as long as it says GL-5 you're good to go. And my opinion is, even though I only tow my boat about half the year and wheel about once a month or so...why not put in the 85W-140? I'm not a heavy off-roader and my boat only weighs about 1800 lbs but I'd rather be protected. Can't hurt, right?

    Bob
     
  14. theroofable

    theroofable Full Access Member

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    Yes, I would like to add the 85w-140. Same view as mine. Im not worried about rtv leaking, I use it at work quite often. What happens if it oozes back into the fill area? Do you put it on the outer part of the diff cover? I saw one on youtube where they applied it and then rubbed it to all contacting surfaces. Thanks for the help guys, I really needed to get this project on the road.
    Also, when changing, just jack them up a few inches to get the right fill level?
     
    Last edited: Jan 7, 2012
  15. first&lastKJ

    first&lastKJ Full Access Member

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    85-140 front and rear? Or 85-140 rear only, and 80-90 front. I do tow two times a year about 1600 miles, single axel trailer about 1800 lbs.
     
    Last edited: Jan 7, 2012
  16. theroofable

    theroofable Full Access Member

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    Uh Im pretty sure 85-140 in both. Like stated earlier, its better for them anyway.
     
  17. first&lastKJ

    first&lastKJ Full Access Member

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    Thats what I wanted to know. Thanks.
     
  18. theroofable

    theroofable Full Access Member

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    I believe it says that in the first post. I could be wrong, others feel free to correct.
     
  19. 67Customs

    67Customs Full Access Member

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    My owners manual says 75W-140 only for the front and either 75W-90 or 75W-140 (towing) in the rear.

    However, the Factory Service Manual says 80W-90 for the front and either 75W-90 or 75W-140 (towing) in the rear.

    So, not even Chrysler gives me a straight answer.

    I just go with 75W-140 in the front and rear even though it costs more. I tow quite a bit during the summer.
     
  20. TwoBobsKJ

    TwoBobsKJ Full Access Member

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    As tjkj2002 explains in one of his posts on this thread the diffs are not pressurized systems and therefore the lubricant isn't forced into all areas of the differential - it is a "splash" system. The synthetic oils don't stay on the gears throughout the rotation as well as thicker 'dino' oils do - so going with a synth really isn't as good for your system as an 85W-140 dino oil.

    You're spending money on a synthetic oil that doesn't do as good a job as a dino oil. Think of it this way: If it makes you feel better you could buy a gallon of 85W-140 for half the cost of a quart of full synth, change your diff oils twice as often and still save money! :party52:

    Bob