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What Motor Oil??????

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  • What Motor Oil??????

    Hello there I'm sure this question has been asked and answered before but I want to ask for myself.
    I'm very curious as to what everyone is running for a motor oil in their Mercruiser's???? About to change the oil in my 98 4.3 merc and would like to hear what everyone is running and what they recommend!? Also I do hear of guys running 15w40 oil for diesel motors? Curious about this also! And does anyone recommend running synthetic motor oil????
    Thanks for you time!

  • #2
    Re: What Motor Oil??????

    Originally posted by Dmaxx85 View Post
    Hello there I'm sure this question has been asked and answered before but I want to ask for myself.
    I'm very curious as to what everyone is running for a motor oil in their Mercruiser's???? About to change the oil in my 98 4.3 merc and would like to hear what everyone is running and what they recommend!? Also I do hear of guys running 15w40 oil for diesel motors? Curious about this also! And does anyone recommend running synthetic motor oil????
    Thanks for you time!
    Please, pretty please...just do a search for "oil" with the provided search function. There are thousands of opinions already given on this subject...seriously!

    Comment


    • #3
      Re: What Motor Oil??????

      Get out the
      83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

      1996 Crownline 202BR
      5.7l EFI 0f791070
      Bravo I drive

      GMC Yukon tow rig

      Comment


      • #4
        Re: What Motor Oil??????

        Originally posted by Dmaxx85 View Post
        Hello there I'm sure this question has been asked and answered before but I want to ask for myself.
        I'm very curious as to what everyone is running for a motor oil in their Mercruiser's???? About to change the oil in my 98 4.3 merc and would like to hear what everyone is running and what they recommend!? Also I do hear of guys running 15w40 oil for diesel motors? Curious about this also! And does anyone recommend running synthetic motor oil????
        Thanks for you time!
        Ayuh,..... Yes,......

        I maintain a fleet of barges, that all get 15W-40 Rotella T motor oil,...
        My personal barge, with a 4.3LX gets Mobil 1, 15W-50,....

        Comment


        • #5
          Re: What Motor Oil??????

          DM I went to walmart and bought 20-40.. it works just fine.. if you feel better buying synthetic, go for it.. not necessary.. MHO
          "Na ise kalyteros anthropos apo ton patera sou"

          (greek= Be a better man than your father)....

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          • #6
            Re: What Motor Oil??????

            Engines stopped failing many years ago from oil. They all fail due to manufactures defect and lack of maintenance, lack of maintenance is number one. What ever you use, changing it regularly
            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
            07 Seadoo GTX
            Merc Adults Only VP Adults Only
            G-Dad always said "First Liar doesn't stand a chance"

            Comment


            • #7
              Re: What Motor Oil??????

              Diesel motor oil uses a molecular base very similar to synthetic oils plus it has an additional amount of additives like anti wear, anti foaming, extreme pressure and increased detergents (sludge depressants) and it cost less then synthetic IF cost is an issue for you.
              Diesel oil is formulated to survive in increased pressures and mileage their engines are required of. Its fine for a boat but not so good for car or truck engines that have cat converters because its high sulfur content that will harm the catalyst.

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              • #8
                Re: What Motor Oil??????

                You have many good choices....and a few to avoid....what I'd NOT use is any automotive based 5w/30, 10w/30 or 10w/40...
                here are some good ones...
                Merc 25/40, straight 30 or 40, or 20w/50, or the 15/w/40 that is both gas and diesel certified.
                1988 Four Winns 200 Horizon
                4.3 OMC Cobra

                98 Jeep Grand Cherokee 4.0 Selectrac
                07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                "While air doesn't freeze....rust never sleeps"

                Comment


                • #9
                  Re: What Motor Oil??????

                  Originally posted by AllDodge View Post
                  Engines stopped failing many years ago from oil. They all fail due to manufactures defect and lack of maintenance, lack of maintenance is number one. What ever you use, changing it regularly
                  Yup. I have never heard of a motor blowing up from the wrong oil.
                  2013 Bayliner 255CR
                  5.0MPI S/N:2A044802
                  http://seawenchnc.blogspot.com

                  Comment


                  • #10
                    Re: What Motor Oil??????

                    yeah, me neither, but i still pay the extra $ for the good stuff.
                    Still cant figure out why member Lou C says we cant use automotive based oil like a good quality 10W-40 ?

                    Comment


                    • #11
                      Re: What Motor Oil??????

                      On my Sunrunner I didn't use anything special because we only got about 15 hours a season. I kind of used Bondo's grease rule for oil.
                      83 Sunrunner 16.5 120 merc Alpha 1 drive SOLD 8/1/13

                      1996 Crownline 202BR
                      5.7l EFI 0f791070
                      Bravo I drive

                      GMC Yukon tow rig

                      Comment


                      • #12
                        Re: What Motor Oil??????

                        Car oil is not formulated correctly for the work a boat engine has to withstand. I'm sure you don't drive you car around at WOT all through town like you do your boat on the lake. If you do I'm sure your car is a pile and you no longer have a drivers license.

                        Stick with the quicksilver oil.
                        Last edited by Watermann; April 18th, 2014, 03:36 PM.
                        1979 V5 SS140 HP Merc ...... 1970 18' Chieftain IO restoration
                        1978 16' SS160 SeaNymph .. 1978 14' Seafarer

                        Comment


                        • #13
                          Re: What Motor Oil??????

                          Because its going to shear down in use and then you will be posting "after my boat came off plane the oil pressure gauge read 5 psi, why is that happening"
                          Car engines don't run at 3500-4000 rpms in normal use right? Well marine inboards do. So car based oil is inadequate. NOT one engine marinizer recommended car based oils. They all recommend something you would not be using in a car. Its good to question things sometimes but don't think you can out smart engineers. They specify what they do for a reason. Yeah, yeah I heard all the conspiracy theories about Merc and their special oil. Well the car companies do the same thing. Chrysler with their ATF+4 which was not in the aftermarket for a long time, the Japanese cars that all use some proprietary auto trans fluid, etc. I use what they say and guess what I have had minimal problems over the years.
                          1988 Four Winns 200 Horizon
                          4.3 OMC Cobra

                          98 Jeep Grand Cherokee 4.0 Selectrac
                          07 Jeep Grand Cherokee Limited 5.7 Quadradrive II

                          "While air doesn't freeze....rust never sleeps"

                          Comment


                          • #14
                            Re: What Motor Oil??????

                            Motor oil - Wikipedia, the free encyclopedia
                            94 Formula 27PC Custom 509MPI MEFI3 , B3 XR
                            95 Rinker 232 w/ 7.4L Carb 0F425011 B1 0F486471
                            07 Seadoo GTX
                            Merc Adults Only VP Adults Only
                            G-Dad always said "First Liar doesn't stand a chance"

                            Comment


                            • #15
                              Sign up today
                              Re: What Motor Oil??????

                              Gee, after reading some of these posts, I feel lucky my I/O didn't blow during all the years I owned it using 10w-40 motor oil......

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