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GL-3 Trans fluid

Discussion in 'Daihatsu Hi jet' started by mdfoster, Apr 29, 2022.

  1. mdfoster

    mdfoster New Member

    Last edited: Apr 29, 2022
  2. Roadster

    Roadster Active Member

    GL-4 is spec'd for most manual transmissions now (some use ATF) , and even for my 60's and 70's British cars. - GL-3 is a very old spec. I use Redline MT-90 (GL-4) in all my standard tranny vehicles and like it a lot for shifting smoothness. GL-4 is formulated to not damage brass or bronze synchros etc. unlike most GL-5's with large amounts Molybdenum Di-Sulphide that we use in differentials.
     
  3. Jigs-n-fixtures

    Jigs-n-fixtures Well-Known Member

    The difference between GL3, GL4, and GL5 of the same viscosity, is how they react under extreme pressure. Every number increase they have better adhesion to the gear face when subject to extreme pressure. Basically less gets wiped off during the load. Which isn’t technically correct, but correct enough folks can understand what is happening.

    If GL4 is recommended, then a GL3 might not do a good enough job of protecting the gears. As Roadster said the Extreme Pressure additives in the GL5, can react with the copper in the synchronizer rings of the transmission and weaken the to the point they quit working, or just plain break.

    Problem is that GL4, can be hard to find. But, many of the GL5s are GL4 equivalent, or will state they are “yellow metal” safe.

    The front axle on my tractor calls for GL4. Looking at the Shell Oil site, which has a system to let you look up, the fluids they recommend for different makes and models and years of tractors. They recommend one of their Spirax oils, Which is a GL4/GL5 rated lubricant.

    I have never looked, but they might actually have the Hijets listed. Nope just the Charade.
     

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