Leaky risers from bad gaskets can cause water to enter the cylinders. This can cause engine to stop. As the water drains past the piston rings it enters the oil. I thought my head gasket blew because I found water in the oil as I was changing it to get it ready for the season. I remove the head, but the gasket was fine. Turns out the Riser gasket needs to be replaced every couple of years apparently. Had I known this, I would have likely taken the spark plug out of all of the cylinders, crank the engine over several times to get as much water out as possible, leave the spark plugs out to let the water evaporate off of the top of the Pistons, throw a few squirts of transmission fluid into each cylinder put fresh plugs in, change the Riser gaskets, change the oil, fire it up and let it run to burn any additional water out of the cylinder, change the oil again. Run it some more and check the oil. I suppose it depends on how New your engine is as to which route you want to go. The only other route, is to remove the heads, get the cylinder walls cleaned up, replace the head gaskets, the risers, the oil etcetera. That would be the proper route.
