Yamaha F250 four stroke. it is a 2008 model. This is Yamaha's commercial model. Over the past year we have replaced the exhaust manifold (all parts and seals) oil pump and seals, crankshaft bearings and all seals, head gaskets and valve stem seals. Engine runs fine but I use the boat to go fishing out on the edge, so I have re powered the boat with a new engine. Although all the seals and gaskets have been replaced, I did not replace the piston rings, so the engine still burns a little oil.