Is Quicksilver oil essential, or can normal oils be used?

[FluffyDog6]

Is the $35/gal Quicksilver oil essential for the Mercruiser, or can normal motor oil be used in it's place? (It seems like anything with a picture of a boat on it costs double what the non-boat version costs.)

How much oil is required for a 1988 Mercruiser 5.0 V-8 motor -- would I need another quart to go with the gallon, or does it take less than a car motor?

I'm in a situation where I can't get into the boat to look at these things for another couple of weeks due to mandatory overtime at work.

Thanks.

[mmwjr]

You 5.0 should require 5 quarts of oil. There are differences in how a boat engine operates vs a car engine primarily being a boat engine typically operates at 3000 rpm under heavy load pushing a boat through the water where a car engine is closer to 2000 rpm with lighter load since it’s only working against rolling resistance. This requires the marine oil to hold up under these conditions and is formulated as such. While automobile oil can be used it would need to be high end oil which cost is close to marine oil. IMO it’s not worth the risk of the possibility of engine wear considering most only need to change oil once a season.