I’m looking at a preowned boat. The owner told me, has had the same gas in it for eight months. Only took it out twice. It has No conditioner in the gas tank , he took it out last week and it ran fine. If I crank the boat and it starts fine runs fine, am I OK. I am an experienced boater, but this is a little bit new to me having one had the gas in it for that long. I do know about putting conditioner in and I’m very familiar with it and plan on doing that when I get the boat
It’s a 2009 mercury OptiMaxx 150. I’m going to look at the boat tomorrow. If anyone can help me with this, I would greatly appreciate it.

Get the garbage gas out now. That motor won’t tolerate phase separated gas. Put it in your truck, kill fire ants do anything but run it again.

I’d put a couple of cans of sea foam and try to find non ethanol gas to top off.

Yes get rid of that gas. Then put Stabil in when you gas up. Btw i am curious, never really did a search. But i have a 2ooo Merc 200hp. E F I been running just reg. gas [87octane] Never had any issues with it. for 8yrs. iam not a go fast, wot guy. Usually 40/45mph. is higher oct. recommended??? Thanks

I think you would be wasting your money running higher octane. I have a 2006 200 Optimax and it runs fine with 87 10% ethanol. I normally run Sea Foam in it. I ran 93 in my Black Max but only because I had milled heads and high compression.

Those motors are made for 87 octane gas.

I really like the Seafoam, it actually helps if you catch it before the idle jets and or high speed jets stop up. But I would not use Stabil in anything. I have no idea how many carbs I have had to clean and re-kit to find that the Stabil was what I found all gummed and sticky inside the fuel bowls. You could not only see the yellow looking stuff but could smell it.

Yes I am sure it will help your fuel last longer, what I have seen though is it leaves a substance behind that is too tacky. You use your gas up and not fill your boat till your going to the lake and use the Seafoam is a much better plan. You keep fuel on board for more than 45 days, our outboards should not be using it.

I use the Seafoam in mine about every 200 Gallons, now what I also use and every time I go add fuel is I use 1oz of Yamaha Ringfree Plus to every 10 Gallons of non-alcohol fuel I put in. I recently found a local place that sells 91oct non-alcohol fuel. They sell lots of it too. That is important also, they need to sell lots of it.

Our outboards will do fine on 87 for the most part, where things change up is if you get out on the lake and you make long runs to a fishing hole at 4500rpm's or more, sustained higher speeds. Just like our string trimmers and stick edges or chainsaws, the better octane non-alcohol fuel really makes a big difference. I flat will not use any fuel that has the alcohol in it in my outboard or lawn equipment. I also make sure to add the Yamaha Ringfree Plus in that fuel also. You either pay now or pay later.