Dear MOby,

I have 370,000 km on my 1983 Honda Gold Wing and I have a problem with my clutch. I rebuilt the engine by the book at 280,000 km. Everything is now obsolete. The clutch works fine as long as I have used,  dirty oil. But when I give it an oil change, the clutch drags slightly and slips. As the oil gets older, it starts working fine. I know the aluminum clutch basket is worn but I cannot replace it. Could it be the oil I’m using? Is there a special oil for wet clutches?

Ken Soderquist

Somewhere Exotic, Sounds Like


Dear Ken,

Wow, 370,000 km sounds like nearly 230,000 miles. Good on you for keeping it rolling for such a long time. In answer to your question, YES, there most certainly is a special oil for wet clutches – or a special certification at least. JASO (Japanese Automotive Standards Organization) designates oil designed for motorcycles with wet clutches “MB” or “MA.” These do not contain the “friction modifiers” that help automobiles get great fuel economy but are so slippery that they cause wet clutches to slip. 

Wet clutches are, of course, common in most motorcycles but rare in automobiles. A wet clutch is bathed in the same oil that lubricates the rest of the engine. Some motorcycles have dry clutches (BMW’s Boxers and several Ducatis, for example), but they’re the exception rather than the rule.

MA was the original wet-clutch oil designation, MB is a lower-friction oil that’s also wet clutch-friendly. Unless your manual asks for MB, MA is what you want to use in your bike. MA2, like the Suzuki ECSTAR bottles in the lead photo, are a step up from MA. 

If you want more information, a good place to start is here at Oilspecifications.org, which appears to be sponsored by a couple of oil companies but has good information. The need for MA doesn’t necessarily mean you’re restricted to buying expensive, motorcycle-specific oil. The stuff I use in nearly all my vehicles just to simplify my life – Rotella T6  Synthetic – also carries the MA, MA2 and MB stamps of approval right on back of the gallon jug you can find in most of the big box stores.

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  • Starmag

    Slip slidin’ away
    Slip slidin’ away
    You know the nearer your destination
    The more you’re slip slidin’ away

    • Old MOron

      There must be fifty ways to leave your old bike.

  • john burns

    Geek Chorus.

    • Starmag

      I knew you’d come throuigh in the clutch and slip something in.

  • DickRuble

    “Is there a special oil for wet clutches?” – yes, it’s called “diesel engine oil” and it’s 1/4 the price of the so called “motorcycle oil”, and works the same or better.

    Disclaimer: This post is for entertainment only and if your 300,000 mile rolling pile of crap blows out because you got confused and used transmission fluid, that’s your problem.

  • john phyyt

    “I rebuilt the engine by the book at 280,000 km..
    I know the aluminum clutch basket is worn but I cannot replace it”

    Boy that made me laugh. I rebuilt a small block at huge expense and time; A beautiful job. Totally “cooked” the motor after less than 3 k miles . GF driving it and didn’t notice it getting hot ( broke a bottom radiator hose clamp. Which was still on the new hose ).. If you have got 90 k Km from rebuild I guess it is time to do it again.

    • DickRuble

      A temperature warning flashing light coupled with a siren wouldn’t be that expensive and would save mucho heartache. Either that or don’t let the keys out of sight next time.

      • john phyyt

        Yes. yes.. But I like sex . And if you look like me : well sometimes you have to pay for it. In many ways.

  • thats a lot of miles! nice !!

  • ChiefPockets

    Only BMW’s older boxers have dry clutches. When they added water cooling they moved the clutch to the front of the engine and dunked it in oil.

  • Foo Cue

    You’ve been riding many moons on your Gold Wing, with amazing endurance for sure! I’ve found that my wet clutch Honda does best with Pro Honda GN4 (MA) oil with the special additive moto package, either 10W-30 or 10W-40, depending on where you live and the heat range. Car oils do not work as well with new or well-used wet moto clutches. Additives usually make the oil even more shear-slippery, especially when taking off in 1st gear. Took me awhile to get with the right oil program, but it works.