A Friend of mine has a 97 502 MPI with oil temp at 290 at WOT. The motor is all stock with 415 horse. The oil cooler is mercruiser standard for the motor and is mounted verticly in front of the motor. The water temp is 150 at WOT. The oil pressure gauge never changes. It is allways 40 pounds. There is a remote oil fiter installed and that is where the sender is located. The oil is mobil 1 15/50 syn. Boat is run on lake michigan. Any suggestions on where to start would be appreciated.

I Had The Same Problem Over The Weekend But It Happened All Of A Sudden,im Going To Pull Off The Oil Cooler And Clean Out,a Restriction It It Can Cause Oil Temp To Climb.then If Oil Temp Goes Up,pressure Goes Down.some Motors Also Have An Oil Tstat In The Filter Housing.im Trying Everything