I have a 23' Cheetah with a 2000 6.2L Mercruiser/Bravo1 and I need some oil advice. I have the Selco manual it says to only use 25-40 oil. The previous owner used 20-40 and the shop I had do my maintenance (didn't feel like doing it myself) said they use 20-50 in all boat motors.
Anybody have any input or reasons why I might want to drain the 20-50 and put 20-40 back in.