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Lower Unit Gear Oil ???

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  • Lower Unit Gear Oil ???

    Can modern 75w140 synthetic gear oil be used in my 1980 Evinrude 115hp Lower unit? I ask this because I happen to have about 8 qts of this gear oil.

  • #2
    Re: Lower Unit Gear Oil ???

    My guess would be yes, and if I had it I'd use it, but will defer to someone with that vintage of engine. It's too new for me.


    • #3
      Re: Lower Unit Gear Oil ???

      If it is not an outboard engine gear oil it won't contain the additional corrosion inhibitors to guard against the effects of water ingress.
      If it is just, as I suspect, an automotive oil, then the objections to using it on this basis are just as valid as the objections to using automotive sae 80/90 oil.


      • #4
        Re: Lower Unit Gear Oil ???

        Agree, you will save $5 using the oil you have but may cost yourself a lower, it just isn't worth it.

        Lower oil has stuff in it that auto oils don't because the engine operates in a completely different environment.
        GO IRISH!!!!


        • #5
          Re: Lower Unit Gear Oil ???

          Marine oil is a special hypoid oil, which will mix with a small amount of water and still maintain it's lubricating properties. Automotive oils won't do that.


          • #6
            Re: Lower Unit Gear Oil ???

            Thanks for the replies.


            • #7
              Re: Lower Unit Gear Oil ???

              Something to ponder!! GL5 is GL5 whether it is marine or auto. Water is a darned poor lubricant. Marine GL5 "supposedly" has "more" emulisifiers in it which allows water to mix with the lube should you have a leaky gear case. Since water doesn't lubricate well, why mix it with the lube that does. So either way, the gear case will not live long if not repaired. I've used auto GL5 (because I had it on the shelf) and because I did does not mean you "should". But my feeling is that in a properly sealed gear case, either will work just fine. Marine GL5 is yet another way to extract another buck or two from your wallet.


              • #8
                Re: Lower Unit Gear Oil ???

                Here is some good gear oil test info. This link has been posted here before several times.