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Cleaning and flushing the transmission

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  • Transmission / Overdrive: Cleaning and flushing the transmission

    The shop manual for the 1951 Passenger Car ( I'm working on '52 Land Cruiser, T86 with overdrive) says to "drain, flush, fill" the transmission every 10,000 miles. It identifies the appropriate oil for the transmission, S.A.E. 90 high grade mineral oil gear lubricant, but what is the appropriate fluid to flush it and to flush the OD unit? I have the transmission opened up sitting on my bench and would like to clean it up as much as I can without disassembling it. What is the best/safest way to clean the old oil residue off the gears that I have access to? Pete

  • #2
    I drained and put in ~ 2+ pints of kerosene, up on jack stands and @ idle..... shifted into all the gears, including OD (may not need this).... then drained and filled both boxes with GL-1 from NAPA.....that was ~ 5K miles ago..... so far, so good....comments ??


    • #3
      Diesel fuel is also an excellent solvent for gearboxes.

      jack vines


      • #4
        Is this also good advice for a 3/4 ton truck? Drain, flush & fill with 90W?


        • #5
          I used kerosene to flush the trans and overdrive while it was in the car,then filled them with mineral oil per instructions in shop manual(important).


          • #6
            I'd just drain the oil and replace it with Redline MT-90. If the old oil came out stinking and real filthy, I'd run the RedLine about 1000 miles then drain it and put fresh Redline back in it. Also, see this post:Transmission service