I have a 1986 Crestliner boat with an OMC 3.0L 4 cylinder inboard/outboard engine. This has a carburetor. So far, seems to run very good. For the past year or longer, it has mainly had non-ethanol gas put in it. Can I use “regular gas” (with up to 10% ethanol in it like I put in my car) and use Marine PRO or Sea Foam Motor Treatment?
That’s a great question, AL. Boat engines made prior to 2003 or so are not built to handle the corrosive combination of ethanol and water, so older engine parts will rust, oxidize, or break down easier. You could use ethanol as long as you know you’re going to work through the fuel quickly. If you have to leave it sit in the tank for more than a week I would not put ethanol in a 1986 boat. Sea Foam would definitely help with lubricity, but no treatment is going to change the vulnerability of your boat’s engine (ferrous metal parts) and fuel system components (plastic and rubber). Hope this helps!