What Rear fluid

Discussion in 'The Garage' started by 1BAD96SVT, May 6, 2007.

  1. 1BAD96SVT

    1BAD96SVT Member

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    Im looking into changing my rear end fluid to royal purple on my cobra,how many quarts to i need and what weight should i go with..?
     
  2. Lightning Struck

    Lightning Struck Legend

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    2 quarts of 75w90 is what went in mine if I remember correctly :dunno:
     
  3. riored96gt

    riored96gt Active Member

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    When I swapped to Royal Purple in February, it took just over 2 qts...
    Don't forget the Ford traction Modifier!! $5 at a dealer
     
  4. Maniak87

    Maniak87 Member

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    is the modifier needed? i am assuming yes... what weight royal purple did u go with?
     
  5. 97blackgt

    97blackgt Well-Known Member

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    i went with redline 75-90

    and yeah you need the friction modifier
     
  6. riored96gt

    riored96gt Active Member

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    Yup...75-90.

    No need for 85-140 unless you're road racing.

    Without the modifier, the trac-loc won't, consistantly.

    (I could do without the smell, though!)
     
  7. 1FastGT

    1FastGT Active Member

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    what does the friction modifier do? sorry im a noob never knew this existed.
     
  8. MeanGrn Gt

    MeanGrn Gt Well-Known Member

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    friction modifier is needed for the trac loc (limited slip) in the read end. without it the clutches wont function properly and you will be doing :eek:utofcloset: one wheel peels
     
  9. Conechaser

    Conechaser New Member

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    What happens if you use the 75-90 for the road course instead of the 85-140?
     
  10. birel21y

    birel21y Active Member

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    If you use the thinner oil, its just not as much protectionon the ring and pinion. Your full throttle alot of the time, and the ring and pinion are turning crazy fast. More heat = thinner of oil, to compansate, use a thicker oil to start.

    Same reason why we use 15-40 oil for the engine.