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, 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.

Send your moto-related questions to If we can’t answer them, we’ll at least make you feel temporarily better by thinking you’re talking to somebody who cares. And remember, only the Pope is infallible. But we probably know more about motorcycles.

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