I have a 2006 Mercruiser 6.2 Horizon fresh water cooled. It has approximately 650 hours and I noticed the other day that the oil level was higher on the dipstick. It has water in the oil. I changed the oil/filter and ran it once again and it is higher again. It is not coolant which would rule out a head gasket and must be on the raw water side of the motor. The risers/riser blocks were replaced last season. Any suggestions, I don't know if the motor has an oil cooler but I was thinking that could possibly be the culprit. TIA

You say it's fresh water cooled, then mention it having coolant. Is it a closed cooling system with fresh water heat exchanger?

Lake water goes thru your oil cooler. Very possible the water is coming from there.

I verified that the 6.2 Horizon doesn't have an oil cooler. I might pull the risers and take a look, only other thing I can't think of.

^^^Best place to start.^^^

Any salt water use ? OE exhaust or aftermarket ?

Boat is all salt water use. It has closed cooling with new exhaust risers and riser blocks last year.

OE manifold/risers ?
wet joint or dry joint ?
coolant or raw water thru manifolds themselves ?

Fresh water cooled manifolds, Mercruiser OEM, just pulled all the plugs and no water in the cylinders, changed the oil again. Seems like the oil smells like it has fuel in it, I don't think he has any water in the oil. Now on the search to figure out why it is running so rich.