hey, I have a 1988 four winns with a cobra 5.0(chevy 305). I recently changed oil and put the 6 quarts that my omc shop manual says and nothing showed on the dipstick. Finally after a total of 8 quarts it read perfectly full. Ran it, now after sitting it shows its half a quart past full. the boat is perfectly level sitting in my garage, does anyone know exactly how much oil she should take?