Synthetic oil for K100

  • Hi All,

    I tried to search the for comments on using Synthetic motor oil in a K100RS.

    Unfortunately I only find German threads, and since my German is not too great, is there anyone that can point to an English thread on whether or not to use synthetic motor oil?

    Any discussion or opinion in this thread is also ok, for me ;)

    Thanks, Pete

  • Hi Pete,

    as far as I followed the matching threads to this topic, it seems to be a matter of belief.... When using synthetic oil some write about lots of oil-leakages, damaged valves due to a suddenly clean combustion chambers and not matching valve clearances caused by that, lots of leaky gaskets and damages around the starting engine (Anlasserfreilauf --> I don't know the matching english word).

    Others again tell that they use synthetic oil since years and never had any problem wth that at all. Its hard to judge for me as well which is now fact and which is fairytale. Those statements you will find always without regard of the age of the motorbike or wether its a 2- or 4-valve-engine.

    The last time I let made a maintainance at a BMW-garage, they filled in some modern oil with different viskosity from what I normally used (they told me, its half-synthetic) and I never had a problem with this as well, though I prefer to use mineral oil like 20W50 for my old 2V-K.

    For me, I would not change the type of oil in a not leaking system if there is no special reason to do it. It surely insecures one to read about this and that and so I decided to go on using what was used decades before as well in this engine and which was good at all.
    There are surely some developments done in oil but since I am not sure at all to do or not to do, I stay with what was good until now.


    Dieser Beitrag beruht auf einer wahren Begebenheit. Die Personen der Handlung sind frei erfunden. Jede Ähnlichkeit mit lebenden oder verstorbenen Personen, Firmen, Körperschaften des öffentlichen Rechts, Anstalten, Gestalten und Verunstaltungen sind rein zufällig. Außer Tiernahrung.

  • Hi Klaus, Thanks for your input! I was looking around a little more, and also in the German threads (even though I do not completely understand them) I noticed many different opinions.

    the problem for me is that my K100RS has not been serviced in ~6years, and I do not know what they did back then or what kind of oil they put in.

    The bike has now passed inspection, and I have it completely registered, I drove it for ~250km the last week, but I do not want to drive more without giving it some maintenance (I will do myself).

    I will continue to investigate.... Thanks again.

  • Oil discussions may last for days. You ask two and get three different answers.
    Beside my K (2V) I also drive some elderly BMWs from 70s through 80s. There you always have al lot of oil discussion, too.

    To make it short: the K jus needs cheap mineralic 20W50 Oil. If you use modern synthetic oil, still matching the viscosity required, all will be fine. I never have had problems with leakage. You only should avoid too low viscosity, e.g. 0W40. Use something like 10W60, that will work. Even more when you drive 4V K since they consume some more oil anyway.

    I have put this synthetic 10W60 in my K just because I have a big bin of it in my garage, for all the old cars where it works fine.

    Just make sure NOT to buy JASO MA Oil which has some additives in favour of wet clutch operation which does not apply to the K with the dry clutch but meay affect the starter free run gears.

    Best regards

  • Most problems are reported when you change from Mineral to Synthetic.
    If you change from Synth to Mineral there is no problem.
    A high quality mineral oil for car engines with SAE 15W40 or 20W50 will be fine as suggested before.

  • A high quality mineral oil for car engines

    Cheap oil from a DIY-shop will work as well.
    Goedkoop olie uit een doe-het-zelfwinkel zal ook goed werken.

    "Technischer Fortschritt ist wie eine Axt in den Händen eines pathologischen Kriminellen."
    Albert Einstein

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