I switched over a motorcycle years ago and ended up with leaking gaskets. Thanks for your reply.
There should be no correlation. Motorcycle oils are typically common sump engine and transmission, so they are still API SG (old category). This category had fewer or no friction modifiers, which would have caused problems in the clutch plates. However, this category isn't bad because the antiwear additive level was high; the phosphorus in the additive has been decreased and decreased in newer categories because it is thought to affect catalysts.
That describes the additive package; if the motorcycle oil was synthetic it still should not have mattered since seals, gaskets, elastomers, etc starting in the mid 80's can tolerate synthetic oils just fine. It could (gulp) be that it is just old... like my '94.