88 Turbo LSD oil - Ford 75w90?

+ Reply to Thread
Results 1 to 12 of 12

Thread: 88 Turbo LSD oil - Ford 75w90?

  1. #1
    SupraForums Member outrider's Avatar
    Join Date
    Mar 2004
    Location
    Hudsonville, MI
    Age
    36
    Posts
    77

    88 Turbo LSD oil - Ford 75w90?

    Changing fluids and getting my car ready for spring, and I ran in to a small issue. At the local Ford dealer on my way home from work, they informed me the 75w90 is no longer available, and has been superseded by Motorcraft 75w140 (with or without friction modifiers). They also had a 75w85 synthetic.

    So I suppose the 140 is fine in Ford diffs for which is was designed, but does anyone know if that would be suitable for our cars as well? Would you run the 75w85 instead, or just get a different brand altogether. On a positive note, they do still carry the xl3 friction modifier!

    Thanks for the help!

  2. Remove Advertisements
    SupraForums.com
    Advertisements
     

  3. #2
    7M Fanatic sixpack's Avatar
    Join Date
    Jun 2006
    Location
    San Antonio, Texas
    Age
    66
    Posts
    2,976
    Will be fine.
    In fact, I was surprised to find info about diff lube when searching to find what Nismo recommended for oil when I put one of their LSDs into my 46 year old Datsun truck.
    Above 90*, they say to use 75-140 in both the trans & diff, so they both got the thicker stuff.
    The H190 Nissan diff is nearly the same internally as the Nissan R200, and our 8".

    Even with the thicker oil in the trans, it shifted much better even on 28* winter days.
    Since both the W58 and the Nissan 71B trans are nearly the same (built by the same people/similar power applications), I'm wondering if the people running the W5x wouldn't get better life by using the thicker oil.

    Besides, both oils have the same low temp rating, 75w......

  4. #3
    Super Moderator Wreckless's Avatar
    Join Date
    Feb 2002
    Location
    Albuquerque, NM
    Posts
    9,898
    The friction modifier is garbage for 99.9995% of MKIII diffs. The factory LSD in MKIII's has a very low breakaway torque rating and the age and miles have made that even lower. The purpose of the friction modifier is to lower that breakaway torque (in essence, making the LSD less aggressive) to mitigate NVH/noise/diff chatter problems.
    Now, if you aggressively rebuilt an MKIII diff with a strong clutch stack and started having diff chatter problems or chirping tires when making turns in a parking lot - yes, then use the friction modifier.

    I've been running parts-store Mobil 1 75w140 in MKIII rear ends for over a decade and it works great. No issues.
    Jeff
    "I spent a lot of money on booze, chicks and fast cars. The rest I just squandered." -- George Best
    Quote Originally Posted by KING View Post
    Who would have ever thought.....the impact an automobile can make.....

  5. Remove Advertisements
    SupraForums.com
    Advertisements
     

  6. #4
    SupraForums Member outrider's Avatar
    Join Date
    Mar 2004
    Location
    Hudsonville, MI
    Age
    36
    Posts
    77
    Thanks for the quick replies. I'll run the 75w140 and see how it drives, adding the friction modifier if needed. My car has low miles but it's still 31 years old, and as far as I know the diff has never been opened. Appreciate the help!

  7. #5
    boost'en down 101 black89t's Avatar
    Join Date
    Jul 2007
    Location
    nor cal
    Age
    31
    Posts
    1,217
    if you get the fluid without friction modifier and don't add any i'm pretty sure you'll experience a decent amount of chatter. i've never done it on a stock diff but with new clutch packs, beefy pre89 spring with weir mini spring, and shimmed about .020" on each side without friction modifier my diff chattered horribly. you could feel it throughout the car. that was with redline 75w90ns that has nothing added. the benefit to using fluid without friction modifier is you can fine tune exactly how much chatter you want. most fluids that have it already added have enough to where there's no chatter at all if anything they error on more. you can definitely get a little more grip out of worn clutch packs when running them to where there's a little chatter which for some people that's what they're after
    Last edited by black89t; 04-10-2019 at 09:55 AM.
    89 supra turbo 2jz na-t, hx35 @20psi 476whp/473wtq
    now s364.5 661whp/609wtq @28psi
    90 toyota pickup with 7mgte/r154 totaled :(

  8. #6
    Super Moderator Wreckless's Avatar
    Join Date
    Feb 2002
    Location
    Albuquerque, NM
    Posts
    9,898
    Quote Originally Posted by black89t View Post
    if you get the fluid without friction modifier and don't add any i'm pretty sure you'll experience a decent amount of chatter. i've never done it on a stock diff but with new clutch packs, beefy pre89 spring with weir mini spring, and shimmed about .020" on each side without friction modifier my diff chattered horribly. you could feel it throughout the car. that was with redline 75w90ns that has nothing added. the benefit to using fluid without friction modifier is you can fine tune exactly how much chatter you want. most fluids that have it already added have enough to where there's no chatter at all if anything they error on more. you can definitely get a little more grip out of worn clutch packs when running them to where there's a little chatter which for some people that's what they're after
    I have never experienced a stock MKIII diff that chattered unless it was rebuilt with new clutch packs and Weir parts like yours. This includes seat time in a gorgeous '91T 5-spd with ~50k original miles.

  9. #7
    7M Fanatic sixpack's Avatar
    Join Date
    Jun 2006
    Location
    San Antonio, Texas
    Age
    66
    Posts
    2,976
    I have never even tried running a stock LSD without doing a bunch of work to make it hold more than the wimpy 45 ft/lbs that they hold, even when new, and less after they wear in.

    OP, you may consider just taking the time to drop it out, open it up, and buying some parts from Weir...
    Only thing you have to watch, is what side the bearing shims go to, other than that it's just nuts & bolts, a few parts, and a tube of red hi-temp silicone.

  10. #8
    SupraForums Member plaaya69's Avatar
    Join Date
    Jun 2007
    Location
    Waukegan, IL
    Posts
    793
    I also had my diff rebuilt by a member on here who rebuilds them and here was my specs before and after the rebuild. I also had the weir spring installed:



    I run synthetic Motorcraft 75w90 with 1oz of Motorcraft friction modifier (which was recommended) and the diff handles very well after the rebuild. You still can find the Motorcraft 75w90 on Amazon:

    https://www.amazon.com/gp/offer-list...&condition=all

    This is about $13 more a quart than what I paid in 2017 but if you really want it then I would go for it or even look on Ebay and you might see some listings pop up.
    87 Turbo Supra - Daily Summer Cruiser
    87 Non-Turbo Supra - Sold
    04 GS300 - Daily Driver

    2019 Updated Build Thread - https://www.supraforums.com/forum/sh...ore&highlight=

  11. #9
    7M Fanatic sixpack's Avatar
    Join Date
    Jun 2006
    Location
    San Antonio, Texas
    Age
    66
    Posts
    2,976
    Nice set of numbers there, thanks for posting.

  12. #10

    Join Date
    Jul 2014
    Location
    St Pete, FL
    Posts
    31
    I've used the Ford mixture in the distant past but 5 years ago started using Castrol 80W-90 limited slip. About $8/qt at O'Reilly's. Seems to work fine. I also rebuilt the differential 5 years ago with new bearings and shimed the clutch pack using shims from the Toyota dealer to get it into spec. An additional 0.020" on each side of the clutch pack got the spider gear backlash correct. The breakaway torque is somewhere around 80 foot-pounds. (I have the early fat clutch pack spring) I also used a solid pinion spacer with shims rather than a crush sleeve which is harder to do physically. A transmission jack from Harbor Freight was helpful in removing and installing the diff. It took several passes with the shims to get the pinion pre-load in specification. Only then did I Install the Toyota front oil seal and put it back together for the last time. It's really good to have a brass drift punch around differentials to move things without damaging surfaces. Somewhere along the line I picked up a tool set (Northern Tools) for removing bearings and pulling pinion gears. I modified a flange tool for another differential to work with the Supra flange in order to hold it while tightening the pinion nut before staking. Had to clean up the threads with a feather edge file.



    Castrol.JPG Differential.jpg Diff2.jpg
    Last edited by Bruder; 04-18-2019 at 09:38 PM.

  13. #11
    Sorry to thread jack, but I didn't want to create a new thread. If you think I should, I will.

    I have a 1988 N/A W58 Trans with the G285 differential (4.3 LSD).


    For the transmission,
    Got 3 bottles of Mobil 1 Synthetic Ger Oil 75W-90 - https://www.autozone.com/greases-and...-1-qt/1437_0_0

    For the Differential,
    Got 2 bottles of Valvoline High Performance Gear Oil 80W-90 - https://www.autozone.com/greases-and...-oz/232566_0_0

    Would those work? What modifier do I need for the differential? I didn't realize I had the LSD until I came home and looked at the label showing G285.

    Also saw this but didn't pick it up. Valvoline Synthetic LSD 75W-90
    https://www.autozone.com/greases-and...-oz/977482_0_0

    Or should I get this ? Valvoline Synthetic LSD 80W-90
    https://www.oreillyauto.com/detail/b...ear+oil&pos=10


    It seems like with these 2, I wouldn't need a modifier, is that correct? Should I stay closer to 80W-90?

    I live in North Texas.
    Any help is appreciated.

  14. #12
    Super Moderator Wreckless's Avatar
    Join Date
    Feb 2002
    Location
    Albuquerque, NM
    Posts
    9,898
    Quote Originally Posted by NARFALICIOUS View Post
    Sorry to thread jack, but I didn't want to create a new thread. If you think I should, I will.

    I have a 1988 N/A W58 Trans with the G285 differential (4.3 LSD).


    For the transmission,
    Got 3 bottles of Mobil 1 Synthetic Ger Oil 75W-90 - https://www.autozone.com/greases-and...-1-qt/1437_0_0

    For the Differential,
    Got 2 bottles of Valvoline High Performance Gear Oil 80W-90 - https://www.autozone.com/greases-and...-oz/232566_0_0

    Would those work? What modifier do I need for the differential? I didn't realize I had the LSD until I came home and looked at the label showing G285.

    Also saw this but didn't pick it up. Valvoline Synthetic LSD 75W-90
    https://www.autozone.com/greases-and...-oz/977482_0_0

    Or should I get this ? Valvoline Synthetic LSD 80W-90
    https://www.oreillyauto.com/detail/b...ear+oil&pos=10


    It seems like with these 2, I wouldn't need a modifier, is that correct? Should I stay closer to 80W-90?

    I live in North Texas.
    Any help is appreciated.
    Redline MT90 in the transmission for a W58 or R154 5-spd.

    Mobil 1 75w90 is just fine for the stock G285. Unless you've rebuilt it with the very aggressive Weir spring, shim, and clutch stack kit there is no need for the LSD modifier. It just makes the LSD work even less like an LSD than the already-weak stock LSD does.

+ Reply to Thread

Quick Reply Quick Reply

Register Now

Please enter the name by which you would like to log-in and be known on this site.

Please enter a password for your user account. Note that passwords are case-sensitive.

Please enter a valid email address for yourself.

List your Car(s)

Where you live

Please select your insurance company (Optional)

Your Supra's Vehichle Identification Number (Not visible to the public)

Log-in

Similar Threads

  1. cheaper way to get ford 75w90+modifier
    By Bri7man in forum MKIII (1986.5-1992)
    Replies: 3
    Last Post: 11-05-2009, 06:13 PM
  2. Redline Gear Oil 75w90 vs 75w90 NS
    By Enzox in forum Shops & Part Reviews
    Replies: 2
    Last Post: 12-22-2007, 09:52 AM
  3. Replies: 4
    Last Post: 04-11-2005, 01:29 PM

Posting Permissions

  • You may not post new threads
  • You may post replies
  • You may not post attachments
  • You may not edit your posts
  •