What gas do I use in my boat???

[DanOnTheBoat]

Hi guys, I'm a new boat owner and I still have the question to what is the right gas that I have to use in my boat. I know that I should be using ethanol free gas but where I live here in Ontario, Canada, they don't have ethanol free gas... I have a 1987 Mercruiser 2.5L in my boat and the last time I filled it up I used 87 octane since thats what I read online is okay to run in your boat engine but it's bad to leave it to sit since it contains 10% ethanol. Is it okay if I fill up and mix my gas at every fill up with Stabil 360 and then go out for the day on the water and use the boat? Would that be okay for the engine and for all of the components? Any alternatives to this? I don't mind paying extra for better gas if there is ethanol free. Let me know!

 

[ScottinAZ]

No ethanol free here either. Same engine, just a 1980 vintage… runs fine on pump gas 87, and I add a dash of stabil at each fill up and pump the tank dry end of season.

 

[DeepCMark58A]

Startron is my additive of choice.

 

[Lou C]

I run what they sell at the gas dock, E10 93 octane gas & add marine Stabil. No real problems over the years….

 

[JASinIL2006]

Seems pretty likely that whoever owned the boat before you must have used gas with ethanol... I wouldn't worry about it.

 

[Scott Danforth]

local 89 octane e10 pump swill will be fine

 

[DanOnTheBoat]

Appreciate the replies guys. Would using higher octane be better for the engine? If I use Octane 93 in my instansce, or would that make no difference?

 

[Scott Danforth]

Appreciate the replies guys. Would using higher octane be better for the engine? If I use Octane 93 in my instansce, or would that make no difference?

absolutely no benefit to you, however your wallet is lighter, so the oil companies make more money. to get a benefit from 93 octane, you need much much higher compression than you have in that low power output 2.5 liter Chevy nova motor.

 

[airshot]

Higher octane fuel burns slower and will be less effecient in a low compression engine. 87 or 89 is all you need unless you like spending money.

 

[Lou C]

Agreed, at the dock all they sell is 93 (good for them eh?!) if I could get 89 I'd use it, BTW there is still a sticker on the flame arrestor of my '88 OMC that says to use at least 89 octane gas. I think in heavily loaded marine engines, I'd want to err on the side of higher octane. The problems people have with inboard gas engines tend to be related to constant load, sometimes not being correctly propped, combustion chamber temps are high, raw water cooling is not as efficient at removing heat as a closed system would be, etc.
I think many marine gas inboards wind up needing a top end overhaul way before (in terms of actual engine hours) you'd see that in an automotive application.