Re: SAE 30 for a 1997 5.7 EFI? (Mercruiser)
Somewhere in the early 90s Merc went from 30W to 25W40 for their 5.7. You won't go wrong with 30W but you should be able to get Merc's recommendation on their web site. West Marine stores have access to the info also. Their Sierra oil filter is the 18-7824.