Crusader 7.4 oil recomendations

[556guy]

Time has come to change oil and filters on my new to me boat. Engines are 1983 Crusader 7.4's with approx 650 hrs. Engines show no oil consumption and if it makes a difference, I run them between 2600/2800 rpm.
Do I want to run a single weight or multi? Previous owner left a couple quarts of 40W.
Any suggestions?

Thanks,
Tom

 

[Scott Danforth]

up to you.

I run 15W40, however I run it in nearly everything except the wife's new VW which runs full synthetic.