Greetings,I have an 86 Cobia with a 140hp 3 litre 4cylinder Mercruiser.The motor tag states 30 wt. for the engine oil.I know back then that was the standard but muti weights have come along ways,I notice Merc's Quicksilver line has a 25w40 they state on the can works in all Mercruiser motors.Just wonder what some of you guys are running for motor oil in your motors?