GT-40 Oil Level

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  • chris196
    • Mar 2007
    • 223



    #1

    GT-40 Oil Level

    When checking the oil on my GT-40 it looked a little low, so I added some.
    Then I discovered that the other side of the dipstick was reading higher. It's like one side of the dipstick was getting scraped off as I took it out. So, one side reads at least one inch (maybe more) than the other. It depends on which way you rotate it when putting it in as to which side reads higher.

    The end result is I probably have about 1/2 quart too much oil in there. (I think)
    How big of a deal is that, if any?
  • east tx skier
    1,000 Post Club Member
    • Apr 2005
    • 1561

    • Tyler, TX


    #2
    Overfilling means the engine has more oil to push around. I've always read that this requires that much more power from the engine with no benefit from the additional oil.

    I've not done my end of season oil change on the 98 Nautique yet, but my old MC had the same block and used the same filter as my PCM GT-40. In the past, I would get 4.5 qts in the engine after priming the filter about 1/2 to 3/4 full. So just about 5 qts total.

    When you checked the oil, where was the boat. I've always been made to understand that "level" for your fluids is the position of the boat in the water.
    1998 Ski Nautique (Red/Silver Cloud), GT-40, Perfect Pass Stargazer 8.0z (Zbox), Acme #422, Tunable Rudder.

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    • chris196
      • Mar 2007
      • 223



      #3
      The boat is on a hydrohoist lift.
      It's pretty level and feels about the same attitude wise as sitting in the water.
      I'm not so much worried about power loss, there's plenty of that for me. I'm worried about foaming and can I do any damage with the extra oil.

      Comment

      • jmo
        Senior Member of PLANETNAUTIQUE
        • Mar 2006
        • 710

        • MA


        #4
        I put about 4.5 into my GT-40. When I put 5 in the oil level is way over the fill line on the dipstick and the engine oil pressure runs higher on average than when I have 4.5 in, granted in both cases the oil pressure is within acceptable ranges. With 4.5 in, its dead on at 40 psi most of the time.

        I've heard opinions on the danger of having too much oil in the block, but I have to believe there is a factor of safety built around the recommended capacity as engineers can't depend on the general public keeping oil level within +-2 ounces of the recommended amount. So what does that mean, IMHO I think your okay if you have a little extra in there, just not alot (like a full quart) more.

        jmo
        2018 Ski Nautique 200 TE, H6
        - 2006 Ski Nautique 196 LE, Excalibur 330
        - 2001 Super Sport Nautique, GT40

        Comment

        • TRDon
          Senior Member of PLANETNAUTIQUE
          • Oct 2007
          • 722

          • MN

          • 1985 2001 1993 Sport carb GT40 2003 SANTE Excalibur

          #5
          the problem with overfilling is that the oil will be in the movement range of the crankshaft causing an undo amount of drag on the crank while moving and can more than likelyb airate (sp?) the oil making its viscosity break down significantly.

          Comment

          • jmo
            Senior Member of PLANETNAUTIQUE
            • Mar 2006
            • 710

            • MA


            #6
            TRDon - do you know how much extra oil does it take to induce this condition?
            2018 Ski Nautique 200 TE, H6
            - 2006 Ski Nautique 196 LE, Excalibur 330
            - 2001 Super Sport Nautique, GT40

            Comment

            • chris196
              • Mar 2007
              • 223



              #7
              Originally posted by TRDon
              the problem with overfilling is that the oil will be in the movement range of the crankshaft causing an undo amount of drag on the crank while moving and can more than likelyb airate (sp?) the oil making its viscosity break down significantly.
              That's what I'm worried about. That's what I've always heard referred to as foaming.

              I think I had 4.5 and now I have 5 because like the other poster, I was dead on at 40psi, but now a little higher.
              It's not that big a deal, I have to pull the boat for the winter and I'll do an oil change. They're lowering the lake to help kill duck weed, so I have to get it back home on the trailer.

              Comment

              • cooterroy
                • Nov 2007
                • 1



                #8
                chris196, where are you located. We have had problems with duckweed where my parents have a house in South Texas.

                Comment

                • chris196
                  • Mar 2007
                  • 223



                  #9
                  I'm in Austin.
                  They're lowering Lake Austin for all of January.

                  Comment

                  • DanielC
                    1,000 Post Club Member
                    • Nov 2005
                    • 2669

                    • West Linn OR

                    • 1997 Ski Nautique

                    #10
                    I put 4 1/2 quarts total in my GT-40 each time I change the oil. My 1997 Ski has 1966 hours on it. I use a Motorcraft FL1-A filter, and Valvoline 40W racing oil. changed every 50 hours.

                    Comment

                    • AirTool
                      1,000 Post Club Member
                      • Sep 2007
                      • 4049

                      • Katy, Texas


                      #11
                      The main problem (damage) with oil overfill is that the oil splashes on the bottom portion of the cylinder walls and burns...then gets trapped in your rings thus causing problems with your rings, pistons, and cylinders. Don't run your engine even a half quart over. Just suck or drain some out.

                      Most of the other effects mentioned are not valid.

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