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  1. #1

    Lightbulb 4x4 differential fluid change??

    im going to have my fluid changed tommorow morning, but i dont know if i should use friction modifier or not. i have the g80 rear-end which calls for 80-90w. im not using synthetic oil, so i need to know if i need friction modifier or not? thanks.

  2. #2


    Friction modifiers are generally used for lockers/ limited slip diffs. If you're running an open carrier, you should not need it. Check the FSM to see if it calls for it. Also, if you use Royal purple diff fluid, it already has it.
    1972 chevy p/u - 454 engine - work in progress
    1999 'burb - wife's vehicle
    1976 Jeep CJ5- Dana 60 front and rear, locked, 350 engine, GM 3 spd, Atlas II T/C, 8" lift on 38's
    2003 Jeep TJ- Dana 44 rear Dana 30 front, ox lockers front and rear 3.5" lift on 33's - My DD


  3. #3


    I think that you should put it in seeing as the G80 is a limited slip locker.
    1999 GMC Sierra 2500 350 vortec
    1967 Jeep M725 ambulance 230 tornado
    1990 Cherokee Limited- 3 inch lift on 33's
    ...and every one of em has issues

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  4. #4


    yea it cant hurt to put it in i use it in my truck and i use it in all the trucks i use at work ( which are all fords :( )
    95 GMC Sierra 2500
    3" Body Lift, 33" Goodyear MTR's
    5.7L 350 TBI Edelbrock SDT Exhaust, Flowtech Headers, K&N Intake
    Sold :(
    1999 Jeep Cherokee, 3" Rustys lift, 33" BFG MT's, locked, armored: Rolled :(
    2000 Jeep Grand Cherokee Limited. K&N Intake, Custom Kolak Exhaust

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  5. #5


    well, i put it in and it feels way better than it did hadnt been changed in 116k miles!!! im so glad to have saved this truck from a bad owner. i had both diffs. and the transfer case changed. i cant wait to order my eaton e-locker and put that in, which i will then put synthetic oil in there. i got to see my g80... what a joke! lol

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