Your problem could be as simple as an air bubble as another poster indicated or it could be quite serious. A higher than normal oil level indicates that coolant may be leaking into the oil. That is serious.
Fill all fluids to normal and start the engine. Leave the coolant cap (the one on the engine, not the reservoir) open. At the dock
put the engine in gear
, raise the rpms to about 1,000 and let it warm up. It will take 10 minutes or so to get hot.
Once the engine warms up and the heat exchanger
(the one with the fill cap) is too hot to touch, look down inside the cap. If you see bubbles then that is exhaust
leaking back into the engine water jacket, probably due to a blown head gasket
(or much worse- a cracked block).
A bad head gasket
can also allow coolant to leak back into the engine oil system causing the symptom you noted.
A definitive test for leaking coolant is to pressure up the coolant system (engine off) and see if it holds pressure. This takes equipment
you can buy or hire a competent technician.
On the other hand if all you see is coolant when you look down and maybe see the level is lower than when you filled it cold, then it is an air bubble. Keep adding coolant until it stabilizes.