Diff oil weights

Discussion in 'Technical' started by WazTTed, Dec 27, 2016.

  1. tassuperkart

    tassuperkart Its a lie I tell you!

    But its in a diff. Not gearbox unless I missed something somewhere!!

    E
     
  2. Fists

    Fists Well-Known Member

    Right you are, somehow I forgot what this thread was about.

    So Waztted, what was the issue witg the thicker oil, just noisier cold?
     
  3. Shane001

    Shane001 Well-Known Member

    75w140 vs 85w140 difference is pfft!

    Bigger question is what brand and type of oil was used. Here you may see a difference in similar grade oils.

    PS: I'm running Redline Lightweight Shockproof in my diff. After several track days it still hasn't gone bang. Have run this in my previous race car diff also for several years, never had any issues. Same oil I'm running in my gearbox. And it hasn't gone bang either ;)
     
  4. Fists

    Fists Well-Known Member

    Viscosity around 20-30C is actually about double.
     
  5. Shane001

    Shane001 Well-Known Member

    The 75 / 85 is the cold weight. and it's only 10 difference. ie sweet **** all ;)
     
  6. Fists

    Fists Well-Known Member

    but as I was saying a few posts back (when I forgot we were talking about diffs) the fact that he only made it a couple of ks means the cold weight is relevant, if he'd waited longer it would have ended up the same. Also, the gap between weights gets larger when colder.

    Using redline 75W140 and 80W140 because I can find the info on them viscosity is 180cSt vs 227cSt at 40C ~30% gap and the 85W is going to be thicker again. Not unbelievable that gap is perceptible.
     
  7. Shane001

    Shane001 Well-Known Member

    If you can tell the difference between an identical brand/spec oil 75W140 vs 85W140, in a DIFF, you my friend are the DIFF WHISPERER :p

    There will be sfa noticeable difference in those weights, what you might notice is a difference between say cheap mineral oil vs a quality synthetic.

    And of course getting the correct type of oil. IE for hypoid gears.
     
  8. tassuperkart

    tassuperkart Its a lie I tell you!

    Yes!
    EP rated!
    Speaking of racecars and diff oils. I use a 70% ATF, 30% EP gear oil mix in my racecar transaxle!
    Synchros work perfectly!!!
    E
     
  9. WazTTed

    WazTTed Grease Monkey

    The 85w was a mineral oil and thick as !! Took me ages to pump into the diff itself probably 10 mins of pumping . Compared to the 75w synthetic went in easily about 3 or 4 mins tops
     
  10. Shane001

    Shane001 Well-Known Member

    Yeah I'm thinking there was something wrong with that mineral oil. Should not have been that thick. Maybe it had dino's regenerating ;)
     

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