I got a late 90s kicker that runs like a champ and never misses a beat. But have noticed a small pool of motor oil on the shop floor. Leaks from the exhaust. There is a pretty good sheen of oil when the motor is first started up. Smokes a good amount for a few minutes till is warmed up. Then clears up? Anyone have this problem? There is never any water in the motor or the lower unit fluids. Is it the valve guides or maybe the shaft seal?