Kohler XT675 leaking oil.

I have a 6 year old Toro Recycler 22in front wheel self propelled mower powered by a Kohler XT675 engine. It is leaking oil near the front of the engine. Either out of the muffler or near the OHV case. It has been making a small amount of white smoke on startup and shutdown of the engine. I don't know if that is oil splashing off of the deck and onto the muffler or if it is actually burning oil. Any ideas on what could be wrong or tips on how to find out would be appreciated.

remove spark plug & check compression with gauge, might have blown head gasket. may be able to rent gauge from auto parts store. compression should be approximately 85 to 120psi by pulling starter cord. check 4 bolts at rocker cover for being loose.

First thing you need to do is find a source of the leak. Take a garden hose or pressure washer and clean the engine and deck spotless, then dry. Next start and run the engine for 30 minutes and then let sit for a day. Watch for a source of the leak, if it were leaking as you described I would carefully watch the area around the valve cover. Small amount of white smoke at startup and shut down is normal. Report back your findings.

Ditto to what is already said plus make sure you did not over fill the crank case. I know it is hard to over fill it by much on these engines but that would cause an oil leak at the muffler and some smoking.