Oil turns black fast after oil change

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  • Triam
    • Feb 2026

    #1

    Oil turns black fast after oil change

    Just what the title says. It's noticeably black after less than 500 miles of riding. Does this mean anything significant or is it just par for the course on this bike?
  • JEEPRUSTY

    #2
    How many oil changes has this occurred for?
    If just one then change the oil and see what happens after another 500 miles.

    Comment

    • Nessism
      Forum LongTimer
      GSResource Superstar
      Past Site Supporter
      Super Site Supporter
      • Mar 2006
      • 35790
      • Torrance, CA

      #3
      If the rings are leaking a lot of blow by contamination will enter the oil. A leak down test will tell the tale.

      Sludge in the engine will also contaminate the new oil quickly. Putting the engine on a 1000 mile oil change diet will help clean it up if this is the case. Dropping the oil pan will tell the tale here.
      Ed

      To measure is to know.

      Mikuni O-ring Kits For Sale...https://www.thegsresources.com/_foru...ts#post1703182

      Top Newbie Mistakes thread...http://www.thegsresources.com/_forum...d.php?t=171846

      Carb rebuild tutorial...https://gsarchive.bwringer.com/mtsac...d_Tutorial.pdf

      KZ750E Rebuild Thread...http://www.thegsresources.com/_forum...0-Resurrection

      Comment

      • Triam

        #4
        Well, here's the pan after I first bought the bike. There was no oil going to the top end.



        That was at least 2 oil changes ago. Needless to say that I cleaned that pan up, installed it, then I put some seafoam in my oil and ran it for about 10 miles and drained the oil again. I just changed it to the mobil delvac 1300 (I had car oil in it before, the clutch felt all kinds of funny) so I'll watch the odometer to tell you exactly when it happens.

        Comment

        • Big T
          Forum LongTimer
          Past Site Supporter
          Super Site Supporter
          • Mar 2005
          • 12392
          • West Slope, OR

          #5
          The oil is doing what it should, cleaning the old sludge out of your motor and putting in suspension
          1978 GS 1000 (since new)
          1979 GS 1000 (The Fridge, superbike replica project)
          1978 GS 1000 (parts)
          1981 GS 850 (anyone want a project?)
          1981 GPZ 550 (backroad screamer)
          1970 450 Mk IIID (THUMP!)
          2007 DRz 400S
          1999 ATK 490ES
          1994 DR 350SES

          Comment

          • Guest

            #6
            Hard to tell from the picture, but is that a brass float needle in the pan???

            Comment

            • Chris G

              #7
              Originally posted by azr
              Hard to tell from the picture, but is that a brass float needle in the pan???
              That's what I thought on first seeing the pic, just to add the oil in mine goes dark, not black after a few hundred miles, I've changed it twice now don't know the history of your bike but mine had only done 4k in the last 10yrs so no doubt a build up of gunk in there, I'll just do changes more frequently and keep an eye on it.
              Last edited by Guest; 08-02-2014, 04:55 AM.

              Comment

              • Brendan W
                Forum Sage
                Past Site Supporter
                • Jul 2013
                • 4922
                • Wexford, Ireland

                #8
                I wouldn't worry too much about it. My oil appears dark almost immediately after a change, I haven't seen published figures for these motors but those I have seen quote up to 15% more oil than the stated capacity for a factory fill, i.e. from dry. So there could be 300cc or more, undrainable old oil at every change. I too dropped the pan and cleaned it, still it's dark. The viewing window is dirtier than you think and the metal behind it also giving the illusion that it's darker than it really is. I have an oil leak or two and whatever comes out there is crystal clear - almost. So unless the leaks have some kind of filtering action my oil is a lot cleaner than what appears in the window.
                97 R1100R
                Previous
                80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

                Comment

                • Grimly
                  Forum Guru
                  Past Site Supporter
                  Super Site Supporter
                  • Sep 2012
                  • 5764
                  • Ireland

                  #9
                  One of mine got so bad it was like a constant-loss system. Normally, in personal or commuting use, it would have been tolerable for a while, but in daily constant duty, it became a right pita, so I was forced re-gasket the entire engine on the grounds that if I'm taking it apart it would be a waste of effort to only do one bit. The main bugbear was the standard base gasket leak, and if you're taking it apart that far, everything else needs done while you're at it anyway.
                  This is always a problem with POs, you don't know if they've cheaped out on aftermarket gaskets or not.
                  Dave
                  '79 GS850GN '80 GS850GT
                  Only a dog knows why a motorcyclist sticks his head out of a car window

                  Comment

                  • Brendan W
                    Forum Sage
                    Past Site Supporter
                    • Jul 2013
                    • 4922
                    • Wexford, Ireland

                    #10
                    Originally posted by Grimly
                    One of mine got so bad it was like a constant-loss system. Normally, in personal or commuting use, it would have been tolerable for a while, but in daily constant duty, it became a right pita, so I was forced re-gasket the entire engine on the grounds that if I'm taking it apart it would be a waste of effort to only do one bit. The main bugbear was the standard base gasket leak, and if you're taking it apart that far, everything else needs done while you're at it anyway.
                    This is always a problem with POs, you don't know if they've cheaped out on aftermarket gaskets or not.
                    I'm not quite at total loss, it's about 50%. Over the years I have at great expense developed the ability to meddle with and break working machines. In fairness there have been a lot of exploratory visits to the motor and when that settles down I can think about leaks. Gaskets are in my future but the motivation ( oil loss ) is too small for the moment.
                    97 R1100R
                    Previous
                    80 GS850G, 79 Z400B, 85 R100RT, 80 Z650D, 76 CB200

                    Comment

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