Diff oil weights

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

  1. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    Has anyone tried running a 85w140 diff oil to quieten down some diff whine caused by leader gears and ES urethane bushings .

    Stock weight is 80w90
    Ive Heard of people running mt90 in there Diffs

    ive used a Nulon Diff and gearbox treatment additive and it didnt make much of a difference..

    Diff only makes noise around 90 to 110 otherwise its generally silent, diff had all new bearings and seals when the leader gears where installed so i doubt there is a install issue
     
  2. rob260

    rob260 Moderator Staff Member

    Messages:
    13,303
    Likes Received:
    325
    Trophy Points:
    83
    Location:
    Sydney (North)
    Heavy shockproof
     
  3. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    interesting.. whats that rated at 75w250
     
  4. East Coast Z

    East Coast Z Well-Known Member

    Messages:
    2,804
    Likes Received:
    52
    Trophy Points:
    48
    Richmond Gears include literature with the gear set recommending 85W-140 oil.
    Only an idiot would run MT90 in a Z32 diff fitted with Leader Gears.
    Redline Oils state that Shockproof Gear Oils are unsuitable for street applications, but what would they know.
    I recall when the Leader Gears were being installed by members on this forum a few were identifying diff whine.
    The whine would more than likely be attributed to how the diff was installed, as you know, some mechanics are better than others.
    I had Leader Gears installed by a company that specialises in diffs & there is no difference in noise between the OEM diff & the Leader Gears/Quaife unit.
    You could remove the rear cover on the diff & check the wear pattern on the gear teeth, or alternatively take the car to a diff specialist & see what they say.
     
  5. rob260

    rob260 Moderator Staff Member

    Messages:
    13,303
    Likes Received:
    325
    Trophy Points:
    83
    Location:
    Sydney (North)
    Where? And what would you define as street use?

    In this case (a heavily modified car producing significantly more tq than stock and running a lower final drive) the heavy shockproof is within the specs outlined in the FSM but will offer significantly more gear protection and service life than a "regular" 75w90 or 80w90 gear oil...
     
  6. Fists

    Fists Well-Known Member

    Messages:
    1,453
    Likes Received:
    34
    Trophy Points:
    48
    Shock proof is fine for diffs, it's just gearboxes that don't like it. Not sure if it's good for clutchpack lsds but will be fine for stock vlsd or quaife. Also not good if you've fitted a diff cooler.
     
  7. East Coast Z

    East Coast Z Well-Known Member

    Messages:
    2,804
    Likes Received:
    52
    Trophy Points:
    48
    I'd define street use as any road registered vehicle being driven on public roads.

    How many Z32 diff failures have you seen, or heard of, directly related to the factory specified oil being used?

    For use in a Z32 TT Redline Oil recommends: "75W90 GL-5 Gear Oil
    Most popular Red Line gear oil, with thousands of applications for passenger cars, light trucks, and racing vehicles"
     
  8. rob260

    rob260 Moderator Staff Member

    Messages:
    13,303
    Likes Received:
    325
    Trophy Points:
    83
    Location:
    Sydney (North)
    None, but in situations where the operating parameters exceed factory specs what possible harm can come from using a lubricant the meets and exceeds the capacities of the factory specified oil? It's really no different to engine oil, coolant, brake & clutch fluid etc...

    I'm sure the GL5 75w90 is a good oil. If the data from redline is to be believed (https://www.redlineoil.com/content/files/tech/ShockProof Gear Oil Tech Info.pdf) the shockproof will behave in much the same way but provide a thicker film and improved buffering between gear teeth, which in this case may go some way towards alleviating the problem. The only down side is the cost, but that shouldn't be more than $10-$20 per service.
     
  9. Shane001

    Shane001 Well-Known Member

    Messages:
    1,840
    Likes Received:
    41
    Trophy Points:
    48
    shockproof can be used with clutchpack LSD's only they'll be noisy as no friction modifier. Fine for race use but would be way to noisy on the street.
     
  10. brisz

    brisz Well-Known Member

    Messages:
    3,352
    Likes Received:
    89
    Trophy Points:
    48
    I think this is good advice.
     
  11. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    I hadn't heard that Richmond recommend 85w140 so I'll give that a go ,
    The shop that set my diff up were. Trans and diff specialist I do believe that they have set the diff up correctly they said the wear pattern was spot on .

    I'd say most of the noise is due To the es bushings .
     
  12. Shane001

    Shane001 Well-Known Member

    Messages:
    1,840
    Likes Received:
    41
    Trophy Points:
    48
    Ah but did they set it up according to the instructions that came with the gear set? These gears need to be setup specific to the included instructions.
     
  13. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    Yeh they said thy followed the instructions and I printed out the diff service section in the fsm
     
  14. Claymen

    Claymen Active Member

    Messages:
    1,750
    Likes Received:
    1
    Trophy Points:
    38
    I might have mine in soon enough to compare ;)
     
  15. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    haha good,
    for anyone wanting to know dont try a 85w 140 its way to thick !! tried that for about 3 kms and ditched it.

    back to 75w 140 synthetic richmond oil
     
  16. Madcow

    Madcow Active Member

    Messages:
    1,658
    Likes Received:
    14
    Trophy Points:
    38
    I have the ES bushes in my diff and subframe. its noisy as fk with a stock diff.
     
  17. MagicMike

    MagicMike Moderator Staff Member

    Messages:
    7,388
    Likes Received:
    121
    Trophy Points:
    63
    My leader gears are noisy as also, only between 90 and 110.
     
  18. WazTTed

    WazTTed Grease Monkey

    Messages:
    6,171
    Likes Received:
    44
    Trophy Points:
    48
    cheers for the info, im glad im not the only one :) :D:D:D:D ill just crank up the tunes for now no big deal !!
     
  19. tassuperkart

    tassuperkart Its a lie I tell you!

    Messages:
    2,298
    Likes Received:
    23
    Trophy Points:
    38
    Too thick, how?
    Its exactly the same "weight" oil..........

    E
     
  20. Fists

    Fists Well-Known Member

    Messages:
    1,453
    Likes Received:
    34
    Trophy Points:
    48
    I though the same thing but given he only made it 3km it probably was still thicker, guessing crappy shifting cold.
     

Share This Page