How to do a oil change on a boat. In this video I show you how to simply change your mercruiser motor oil. Easy to follow instructions on changing your boats motor oil. I have a mercruiser 3.0 but, this can go for any motor. 3.0 oil change. 4.3 oil change. 5.0 oil change. 5.7 oil change. How to pump oil out of boat. I bought the pactrade marine boat and rv pump.