Oil grade/weight to use

[Boating_Al]

Every time I ask what’s the best oil grade I get a different answer, some people like the multi grade 15W40, others like straight 30/40W. I was leaning toward the straight 40W oil, I boat here in Miami8) and things get pretty hot.

The engine is a 1994 Merc 5.7 with less than 500hrs.

Thanks in advance

 

[vipzach]

Re: Oil grade/weight to use

See this thread, DonS posted a pic, straight out the merc manuel. You could get a different answer from every person you ask. I use mobile1 20w-50. Temps here this summer were in the 100's.
http://forums.iboats.com/bbBoard.cgi?a=viewthread;fid=24;gtid=1165801

 

[stevieray]

Re: Oil grade/weight to use

You can't go wrong going by the book. Why deviate from factory recommendation?

 

[Don S]

Re: Oil grade/weight to use

These are the newest recommendations from Mercruiser