Announcement

Collapse
No announcement yet.

Differential Gear Oil Weight

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

    Differential Gear Oil Weight

    I'm planning on changing the rear diff fluid in the wagon again just to ensure it's staying clean back there after it got new bearings installed.

    I know the typical oil weight is 80W-90. However, I know some later (like '07+) police package Crown Victorias were listed to use 75W-140. I'm currently using the 75W-140 in my '97 over the regular 80W-90. Haven't had any problems thus far in that car.

    However, I'm wondering if the 75W-140 would be okay in an older axle. I'm just trying to extend the service life of components where possible.


    My Cars:
    -1964 Comet 202 (116K Miles) - Long Term Project
    -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
    -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
    -1997 Grand Marquis LS (240K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

    #2
    i have been running mobil 1 75w90 in everything for years.....no issues.

    Should be able to run 75w140.....it is the same axle either way.

    1986 lincoln towncar signature series. 5.0 HO with thumper performance ported e7 heads, 1.7 roller rockers, warm air intake, 65mm throttle body, 1/2" intake spacer, ported intakes, 3.73 rear with trac lock, 98-02 front brake conversion, 92-97 rear disc conversion, 1" rear swaybar, 1 3/16" front swaybar, 16" wheels and tires, loud ass stereo system, badass cb, best time to date 15.94 at 87 mph. lots of mods in the works 221.8 rwhp 278 rwt
    2006 Lincoln Town Car Signature. Stock for now
    1989 Ford F-250 4x4 much much more to come, sefi converted so far.
    1986 Toyota pickup with LSC wheels and 225/60/16 tires.
    2008 Hyundai Elantra future Revcon toad
    1987 TriBurner and 1986 Alaska stokers keeping me warm. (and some pesky oil heat)

    please be patient, rebuilding an empire!

    Comment


      #3
      My ford factory repair manual recommends heavier grade in performance applications.
      Scars are tatoos of the fearless

      Comment


        #4
        For my 2000 MGM, the owner's manual says 80W-90, but the maintenance schedule implies that 75W-140 is so much better for special operating conditions:

        Normal Vehicle Axle Maintenance

        Rear axles containing synthetic lubricant and light duty trucks equipped with
        Ford-design axles are lubricated for life. These lubricants are not to be checked
        or changed unless a leak is suspected, service is required or the axle
        assembly has been submerged in water. The axle lubricant should be changed
        anytime the axle has been submerged in water.
        Non-synthetic rear axle lubricants should be replaced every 3,000 miles or
        3 months, whichever occurs first, during extended trailer tow operation above
        21 Celsius (70 degrees Fahrenheit) ambient and wide open throttle for extended
        periods above 45 mph. The 3,000 mile lube change interval may be waived
        if the axle was filled with 75W140 synthetic gear lubricant meeting Ford
        specification WSL-M2C192-A, part number F1TZ-19580-B or equivalent. Add four
        ounces of additive friction modifier C8AZ-19B546-A (EST-M2C118-A) or
        equivalent for complete refill of Traction-Lok rear axles. The rear axle lubricant
        should be changed anytime the axle has been submerged in water.

        Police and Taxi Vehicle Axle Maintenance

        Replace rear axle lubricant every 160,000 km (100,000 miles). Rear axle
        lubricant change may be waived if the axle was filled with 75W140 synthetic
        gear lubricant meeting Ford specification WSL-M2C192-A, part number FITZ-19580-B
        or equivalent. Add four ounces of additive friction modifier C8AZ-19B546-A
        (EST-M2C118-A) or equivalent for complete refill of Traction-Lok rear axles. The
        rear axle lubricant should be changed anytime the axle has been
        submerged in water.

        2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
        mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

        Comment


          #5
          Sounds like I'll run with the 75W-140. Figure I would ask around first before doing it on that axle.

          The only down side will be the incredibly negligible impact it'll have on fuel economy.


          My Cars:
          -1964 Comet 202 (116K Miles) - Long Term Project
          -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
          -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
          -1997 Grand Marquis LS (240K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

          Comment


            #6
            I use 75W140 also and have no complaints whatsoever.

            Comment


              #7
              Get whatever synthetic you find. 80w90, 75w90,75w140, doesn't matter much. Your nose will thank you for the synthetic whenever you need to remove that cover again in the future.

              Alex.

              Comment


                #8
                With that said, I always thought any of that gear oil was good for ~100k miles. I have no idea, save for going back & looking at the receipts, what was used in our cars. Well, synthetic or not. Didn't realize the non-synthetic stuff was only good for 3k miles. Bah.
                1985 LTD Crown Victoria - SOLD
                1988 Town Car Signature - Current Party Barge

                Comment


                  #9
                  Thats under very specific conditions though.

                  "Non-synthetic rear axle lubricants should be replaced every 3,000 miles or
                  3 months, whichever occurs first, during extended trailer tow operation above
                  21 Celsius (70 degrees Fahrenheit) ambient and wide open throttle for extended
                  periods above 45 mph. "

                  Unless you tow all summer long and mash the pedal constantly its good for more than 3K miles. The synthetic will take that abuse though.

                  I use synthetic because its honestly not much more expensive. I don't know that it does miraculous things but for an extra couple bucks it doesn't feel like a waste.
                  86 Lincoln Town Car (Galactica).
                  5.0 HO, CompCams XE258,Scorpion 1.72 roller rockers, 3.55 K code rear, tow package, BHPerformance ported E7 heads, Tmoss Explorer intake, 65mm throttle body, Hedman 1 5/8" headers, 2.5" dual exhaust, ASP underdrive pulley

                  91 Lincoln Mark VII LSC grandpa spec white and cranberry

                  1984 Lincoln Continental TurboDiesel - rolls coal

                  Originally posted by phayzer5
                  I drive a Lincoln. I can't be bothered to shift like the peasants and rabble rousers

                  Comment


                    #10
                    The maintenance schedule actually implies that the non-synthetic is good for 100,000 miles in police and taxi use:

                    "Police and Taxi Vehicle Axle Maintenance

                    Replace rear axle lubricant every 160,000 km (100,000 miles). Rear axle
                    lubricant change may be waived if the axle was filled with 75W140 synthetic ..."

                    The maintenance schedule also implies that even non-synthetic doesn't need to be changed for regular (i.e. non-police or taxi) use, but I don't see why anyone would want to leave it for more than 100,000 miles. Mine was a nasty gray color well after that point, and I feel a lot better about having fresh stuff in there.

                    2000 Grand Marquis LS HPP, a hand-me-down in 2008 with 128,000 km; 175,000 km as of July 2014
                    mods: air filter box 'tuba', headlight relay harness, J-mod (around 186,350 km), 70mm throttle body, KYB Gas-A-Just shocks, aluminum driveshaft, ARA3 PCM

                    Comment


                      #11
                      I always run 80w90 or 75w90 synthetic. Town Car's diff had no oil in it when I got it, no idea how long it had been like that, no signs of leaking and it was quiet until it ate an axle bearing 10k miles into my ownership. I put conventional 80w90 in it after replacing the bearings in it and all was well with the world aside from a slight whine at very specific speeds, notably 46-52mph and 75+mph. Fast forward a couple years and 50k-ish miles and I ran over something and mangled the diff cover so it was replaced. When I did that I bought Valvoline 75w90 synthetic for the refill and much to my surprise the whine decreased noticeably, its still there, just quieter. So, ever since then I've run the 75w90 synthetic in any 8.8s I've serviced since. Its not much more expensive to run the synthetic stuff if you catch it on sale and its a bit of piece of mind IMO, if it made the whine of a neglected/abused diff quieter then there has to be something to it.
                      -Steve

                      2006 Audi A6 S-Line FWD ~132k miles, stock.
                      1998 Mercury Grand Marquis LS HPP ~102k miles, slowly acquiring modifications.
                      1997 Lincoln Town Car Cartier ~145k miles, Ported Plenum, Gutted Airbox, Mechanical Fan Delete, Contour E-fan Retrofit, Dual exhaust, Cats ran away, KYB Gas-A-Justs, P71 front sway bar, air ride reinstalled, Blinker Mod, Projector headlight retrofit, Caddy 4-note horn retrofit, Wood rim steering wheel, rustbelt diet plan..
                      1996 Mercury Grand Marquis GS 117,485mi. R.I.P. 7/14/12

                      Comment


                        #12
                        My dad believes his 51 Ford has the original gear oil in it. He's had the car since 1972ish and the prior owner from 53-him wasn't much on maintenance. I doubt the original owner changed it in the first two years. It's his claim to gear oil fame right now. Pennsylvania crude maybe? He drives it 50+ miles a week so it's not a garage queen either. I will change it if it becomes mine.
                        1990 Country Squire - weekend cruiser, next project
                        1988 Crown Vic LTD Wagon - waiting in the wings

                        GMN Box Panther History
                        Box Panther Horsepower and Torque Ratings
                        Box Panther Production Numbers

                        Comment


                          #13
                          Must be made from refined whale blubber, walrus & elephant tusks.
                          1985 LTD Crown Victoria - SOLD
                          1988 Town Car Signature - Current Party Barge

                          Comment


                            #14
                            Thread resurrection

                            You guys using the 75w-140 synthetic, did you add friction modifier if you have limited slip? I know most say it comes with it but i've been reading conflicting things... I'm going to change mine and have a bottle of ford friction modifier on the shelf... would it decrease the clutches effectiveness if i add it to fluid that already says it has it in it?
                            -Phil

                            sigpic

                            +1982 Ford LTD-S Police Car. Built 351w, Trickflow 11R 190 Heads, Holley Sniper EFI, RPM Intake+ Hyperspark dizzy, WR-AOD, Full exhaust headers to tails. 3.27 Trac-Lok Rear. Aluminum Police Driveshaft. Speedway Springs+Bilstein Shocks, Intermediate Brakes, HPP Steering Box.

                            +2003 Acura CL Type S 6-speed

                            Comment


                              #15
                              Both of my cars are open diffs, so whether or not the stuff has the friction modifier in it was of no difference.

                              On that matter, however, I’d start with the fluid first if it already has friction modifier in it. As I’ve heard, if it chatters any after adding the fluid with FM already there, add like an ounce of FM and test it again. Usually the fluids with it already added are pretty solid and typically do not need more added.


                              My Cars:
                              -1964 Comet 202 (116K Miles) - Long Term Project
                              -1986 Dodge D-150 Royale SE (112K Miles) - Slowly Getting Put Back Together
                              -1987 Grand Marquis Colony Park LS (325K Miles) - April 2017 + September 2019 POTM Winner
                              -1997 Grand Marquis LS (240K Miles) - The Daily Workhorse & March 2015 + January 2019 POTM Winner

                              Comment

                              Working...
                              X