What do you recommend with old gas

[johnv100]

I bought an 87 22" Chris Craft with a V6 Mercruiser. The previous owner had it sit for about a year with 1/2 tank of gas. I poured a bottle of stabilizer in the tank when a friend did a tune up and oil change. It takes at least 5 cranks to start when cold, but once it starts and warmed up, it runs fine. My friend told me to fill it up with super unleaded to mix the old with the new, but I'm thinking if it runs, let's just try to burn all the old gas, then fill it up. Please advise what I should do. Thanks.

 

[bruceb58]

Re: What do you recommend with old gas

A year isn't too bad. I would just run it. Putting fuel stabilizer in after the fact doesn't really buy you anything other that introducing a drying agent in case there is water in the fuel.

 

[JustJason]

Re: What do you recommend with old gas

Agreed with Bruce.... Just run it. Avoid high rpm, wide open throttle runs for at least a couple of tankfulls. Adding high test the first couple of refill won't hurt anything. Just take it easy a bit when running old fuel.

 

[havasuboatman]

Re: What do you recommend with old gas

You should definately top off the tanks with premium fuel. As gas gets old, it loses it's octane (It's ability to burn without exploding) .
Filling the tanks with fresh high octane fuel will help offset the older gas.
In your other post you said the engine was really loud, low octane/old fuel will cause an engine to ping, because the fuel is exploding in the cylinder instead of burning.
I, personally, would remove the old gas simply because it will have started to "varnish". It's going to leave alot more gunk in your engine. But that is a personal thing.
Bruce and Jason are correct in saying you can run it thru. A year isn't that long, But top off your tank(s) with premium.

 

[ErieRon]

Re: What do you recommend with old gas

What do you recommend with old gas

A very understanding wife...

 

[Knightgang]

Re: What do you recommend with old gas

I too would add a fuel treatment, maybe an octane booster (optional) and top off the tank with fresh fuel. Then I would run it out as quickly as I could. My boat had been sitting for a few years and probably has about 1/2 tank of fuel. I have a good deal of work to crank it and protect it once again. One it fires, it will get a fresh tank of fuel...

 

[steddy]

Re: What do you recommend with old gas

I'm a little paranoid about running old gas through my expensive marine engine, too. I have siphoned out my tank in the past, marked the can as old fuel, and ran it little by little throughout the summer through my bulletproof Honda 300EX engine and my everlasting Kohlers on my tractors. Those engines have extremely easy-to-clean and cheap-to-rebuild carbs.

 

[Jeepster04]

Re: What do you recommend with old gas

Personally I would just run it out then change the fuel filters. Add new fuel and be done with it.

We keep over 100 gallons of gas in our boat and not all of it will be used in a single season so it sits over the winter. We always add marine Stabil to it when getting gas and before winter and weve yet to have any issues.

 

[JustJason]

Re: What do you recommend with old gas

I'm a little paranoid about running old gas through my expensive marine engine

You shouldn't be. Old gas allows detonation to happen at a lower rpm, and a lower load, than it normally would. So if you take it easy on the throttle, and pretend your rig is not a tug, your usually fine. Just keep it 10-20% below the WOT rating.

 

[elkhunter338]

Re: What do you recommend with old gas

There is a product call I think starbright it is an enzyme treatment that is suppose to help old fuel. A year is not bad I would top off with good fuel, use a fuel stabilizer when you top off with new fuel especially if you are not going to run the whole tank of fuel out in a few weeks.
Also make sure if you have a fiberglass tank that you verify ethanol fuel will not eat the tank up. Some fiberglass tanks melt the resin with ethanol depening on when they were made.
I had trouble with a 2 stroke outboard this summer with fuel. The motor would not start cold, but would start warm. Once I put fresh fuel in it it started 1-2 pulls. The fuel was not really even that old, less than 6 months. I now put fuel stabilizer in it all the time.

 

[WizeOne]

Re: What do you recommend with old gas

I vote to top it off and run it out. I just started up my old Mustang that has, at least, 12 year old gas in it. It was pre-ethanol gas and I had added stabilizer to it. The car started right up after 3 years of sitting and it purred like a kitten.

 

[nhtrax]

Re: What do you recommend with old gas

i would add a octane boost, add fresh gas then once its gone cont a good sta-ble regiment.

 

[JustJason]

Re: What do you recommend with old gas

i would add a octane boost

What specifically... does that do?

 

[nhtrax]

Re: What do you recommend with old gas

stale gas has a lack of combustion octane boost should help the firing process

 

[JustJason]

Re: What do you recommend with old gas

stale gas has a lack of combustion octane boost should help the firing process

Ahhhhhhhhhhhhhh....