Trans gear oil - NCRS Discussion Boards

Trans gear oil

Collapse
X
Collapse
 
  • Page of 1
  • Time
  • Show
Clear All
new posts
Previous template Next
  • Bob W.
    Expired
    • August 31, 1981
    • 84
    #1

    Trans gear oil

    I have read several threads regarding synthetic gear oil in transmissions and all have said to stay away. i was considering this (Synthetic Manual Transmission and Transaxle
    Gear Lube 75W-90 API GL-4 (MTG). Has anyone tried it or should I just try and find some good old GL4. Somewhere I read NAPA carries Stalube GL4. Any opinions? My car is a driver and the tranny is a muncie M21
    Tags: None
      • Top
    • Duke W.
      Beyond Control Poster
      • January 1, 1993
      • 15610
      #2
      Re: Trans gear oil

      The original spec was Mil-L-2105 hypoid gear oil. The mil spec was cancelled some years ago and replaced with the 80W-90 GL-5 API spec, not GL-4. Standard GL-5s carry an 80W-90 viscosity rating. It it's rated 75W-90, it's probably a "synthetic" base and more expensive, and most GL-4s are synthetic base.

      You will hear all kinds of stories on the net and promulgated by specialty oil companies about "yellow metal corrosion" with GL-5, but have you ever actually seen any evidence of this on any of these 50 year old transmissions. I haven't! Synchronizers certainly can wear out over time, but I've never heard of any documented cases of sychronizer corrosion, and I'm sure there are low mileage original Corvettes out there than still have the factory fill Mil-L-2105.

      Just buy any brand 80W-90 GL-5 at any auto parts store at about 3 bucks a quart and stop obsessing over gear oil.

      There was no change interval specified by GM, but they didn't project out 50 years. My suggestion for low use vintage cars is every 30K miles or 15 years, whichever occurs first. Same with the axle, especially if it's a Positraction axle, which will need at least on 4-oz. bottle of Positraction additive in addition to fresh 80W-90 GL-5.

      Duke
        • Top

        Comment

        • James G.
          Extremely Frequent Poster
          • May 31, 1976
          • 1556
          #3
          Re: Trans gear oil

          Originally posted by Duke Williams (22045)
          The original spec was Mil-L-2105 hypoid gear oil. The mil spec was cancelled some years ago and replaced with the 80W-90 GL-5 API spec, not GL-4. Standard GL-5s carry an 80W-90 viscosity rating. It it's rated 75W-90, it's probably a "synthetic" base and more expensive, and most GL-4s are synthetic base.

          You will hear all kinds of stories on the net and promulgated by specialty oil companies about "yellow metal corrosion" with GL-5, but have you ever actually seen any evidence of this on any of these 50 year old transmissions. I haven't! Synchronizers certainly can wear out over time, but I've never heard of any documented cases of sychronizer corrosion, and I'm sure there are low mileage original Corvettes out there than still have the factory fill Mil-L-2105.

          Just buy any brand 80W-90 GL-5 at any auto parts store at about 3 bucks a quart and stop obsessing over gear oil.

          There was no change interval specified by GM, but they didn't project out 50 years. My suggestion for low use vintage cars is every 30K miles or 15 years, whichever occurs first. Same with the axle, especially if it's a Positraction axle, which will need at least on 4-oz. bottle of Positraction additive in addition to fresh 80W-90 GL-5.

          Duke
          I SOLD SHELL, UNION 76 AND CHEVRON oil products for 41 years. DUKE IS 110% CORRECT ! In 1988, NISSAN kept blowing differentials in their famous GTP-ZX Race cars.
          CHEVRON SUPPLIED THEM WITH THEIR THEN NEW Chevron Delo Gear Lubricants ESI product, and they had no more failure that year. The product has better ''high heat'' protection. BUT, AS DUKE SAYS ''STOP WORRYING.....HAVE FUN''
          Over 80 Corvettes of fun ! Love Rochester Fuel Injection 57-65 cars. Love CORVETTE RACE CARS
          Co-Founder REGISTRY OF CORVETTE RACE CARS.COM
            • Top

            Comment

            • Jim D.
              Extremely Frequent Poster
              • June 30, 1985
              • 2882
              #4
              Re: Trans gear oil

              Duke and Jim, Thank you for your comments. I've heard all the horror stories about the "alleged" GL-5 problems but have never seen actual evidence of it. Those stories remind me of the "unleaded fuel/must have hardened seats" B.S. that are still being spread (by the machinists that installing them). I run GL-5 lube, have never had hardened seats installed in any motor I've built, and have never had any problems. Much ado about nothing!
                • Top

                Comment

                • Joe L.
                  Beyond Control Poster
                  • February 1, 1988
                  • 43193
                  #5
                  Re: Trans gear oil

                  What would I use?

                  For manual transmission: GM #88900333 OR Red Line Synthetic 80W-90

                  For differential: GM #89021671
                  with positraction add two 4 oz bottles of GM #88900330
                  In Appreciation of John Hinckley
                    • Top

                    Comment

                    • Dick W.
                      Former NCRS Director Region IV
                      • June 30, 1985
                      • 10483
                      #6
                      Re: Trans gear oil

                      I have used synthetic Valvoline GL5 for the last 10-15 years with absolutely no problems
                      Dick Whittington
                        • Top

                        Comment

                        Previous template Next
                        Working...

                        Debug Information

                        Searching...Please wait.
                        An unexpected error was returned: 'Your submission could not be processed because you have logged in since the previous page was loaded.

                        Please push the back button and reload the previous window.'
                        An unexpected error was returned: 'Your submission could not be processed because the token has expired.

                        Please push the back button and reload the previous window.'
                        An internal error has occurred and the module cannot be displayed.
                        There are no results that meet this criteria.
                        Search Result for "|||"