friend of mine has a 600 that seems to have coolant leaking into oil. the oil level rises even after draining a few ounces of oil during a trail ride . where should I start looking for a bad gasket?

 

One thing to remember is that oil pressure in an engine is generally higher than cooling system pressure, so nine times out of ten, if there is a leak in a head gasket, for instance, there will be oil in the coolant. A problem where there is coolant in the engine oil is more likely a mechanical crack in a head or block where pressurized coolant is pouring into the crankcase in a place that is a non-oil pressure scenario. Sorta like a crack in the water jacket of the block which drips into the crankcase oil.