Rear Diff Oil and Addititve?

Discussion in 'Maintenance Shop' started by MBMNemesis, Oct 7, 2009.

  1. MBMNemesis

    MBMNemesis New Member

    01 Ranger Edge 3.0
    I just had to put a new rear diff cover on because mine rusted through, I put the 5 quarts of gear oil in(80w90) and everything is working fine, no jarring or noise during turns or operation. However im not sure if the truck is posi or not and was told that an additive was needed for posi, is my truck posi, what additive should I use? I guess I can just burn out in the lawn to find out for sure, Id rather keep it nice tho. Thanks for suggestions
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  3. junior

    junior New Member

    What does (did) the axle tag say? The 7.5 axle only takes about 2, maybe 2.5 quarts of lube.
  4. OP

    MBMNemesis New Member

    The tag says

    Tag says exactly as follows S330E
    4 10 88 1A02
  5. bowmaster85

    bowmaster85 New Member

    if you jack up the rear end of the truck and turn the one wheel the other shoul turn the same distance. It would also help if you had someone else holding the other wheel to put resistance on it. If your wheel will turn while the other person can hold the wheel with ease, then not posi. if the other person has to put the same amount of force to keep it from spinning as you do spinning it then its a posi. I have never heard of a oil additive for the posi. I know that in my race car we run a posi and run a full synthetic gear lube to make sure the plates get enough lubrication.
  6. junior

    junior New Member

    that means 8.8" axle, 4.10 ratio, standard differential. an "L" on the tag would indicate a locker. you had the cover off, what was inside?
    "friction modifier" , used in clutch pack type posi's has been around since at least the early 60's. I suppose it's possible that the newer metals and machining processes don't need it, but I don't know that for certain.
  7. rangerdude91

    rangerdude91 New Member

    the 4.10 ratio axels take 75/140 with an additive, and the 3.75 ratio takes 80/90 with the additive as well
  8. redrocket

    redrocket New and loving it

    80/90 gear oil dont matter what ratio you got
  9. EricFi1

    EricFi1 New Member

    I just did my 93 with 8.8".. used 2.5qts of valvoline regular 80w-90 and this time Redline Friction modifier (4oz). Last time I used the Motorcraft friction modifier.
    No issues.
  10. kozal01

    kozal01 New Member

    you only need the friction modifier if you have the trac-loc limited slip.
  11. EricFi1

    EricFi1 New Member

  12. greywarden

    greywarden New Member

    so sorry to be bumping this thread but i just wanna ask what brand of additive you are using in your truck? where can i get it also? on the net? etc etc. is that really recommended? what benefit will i gain from using additives? my friend was recommending me to do this but i wanna make sure before i do it. currently planning to get this ford parts
    Last edited: Dec 17, 2011
  13. Hooligan

    Hooligan Rangerholic!!

    If you have a limited slip rear I recommend using this

    It is synthetic and the additive is already in there.
  14. pooleo

    pooleo New Member

    you can buy a bottle of the additive from ford.
  15. EricFi1

    EricFi1 New Member

    Actually the best addtive is the motorcraft additive.
    And yes, if you buy full synthetic, theoreticaly you don't need the friction addtive, however it won't hurt to use it.
    the Motorcraft addtive is made by Redline, so it's an outstanding as it stands.
    I've also been eyeballing LubeGard's friction modifier, but have to wait another 50k to try it out!

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