Good gas goes Bad?

[walkingfish]

Once again i have a question for all you Boaties that have "been there, done that"<br /><br />With pre-mixed fuel in my '89 125Hp Force, i need to know how long the petrol lasts before going bad?<br />I am using 97 octane in the theory that petrol loses octane with age, and if i start higher then it will last longer before turning to crap?!<br /><br />What problems will i have if the gas goes bad?<br />How can i avoid it?<br />What is the best rules to follow with gas to ensure a long and happy engine life?<br /><br />Again i am looking forward to hearing all adventures you may have had!<br /><br />Thanks,<br />Brad<br /><br />1989 Baliner Capri, Cuddy - 125 Force

 

[mtp]

Re: Good gas goes Bad?

"Life" depends on temperature as well as age, higher temperatures degrade gas faster (the volitile components degas and leave "gum"). Put a fuel stabilizer in tank (premix with 2-5 gallons of gas then add, works for tanks that are almost full. Different stabilizers give different "life" times. Some stabilizers "do" more.

 

[12Footer]

Re: Good gas goes Bad?

4 to 6 weeks at 85deg F (as a rule-of-thumb).<br />Gas turns into varnish..Literaly. This is what varnish is,albeit,much more refined.<br />This varnish will cost you money and time,and could also strand you in the water<br />with a clogged pick-up tube, stuck float needle,and other "day enders".<br />Some boaters like to run the fuel out of their carbs before loading the boat,and I have done this on occasion. But it's not the answer,as running a 2cycle out of fuel also runs it dry of oil. But this prctice helps by reduding the amount of potential varnish in the fuel system. The best thing to do,is run the engine just until the RPMs increase on it's own,and quickly shut off the ignition. Don't allow it to stall from lack of fuel.<br />You can usually smell stale gas. It will smell "varnishy". Hope this helps.

 

[12Footer]

Re: Good gas goes Bad?

Oh yea, forgot something. If you plan to use a fuel stabilizer,use a lower octane fuel,as additives tend to INCREASE the octane of most fuels.<br />The shop manual for your engine recommends<br />87 Octane.

 

[JB]

Re: Good gas goes Bad?

Howdy. That 87 octane the manual recommends is unleaded regular, U.S. "pump" octane rating of 87. In New Zealand and elsewhere it would be a different rating method. Use the octane required by the typical auto.. . .unleaded and alcohol free.<br /><br />Cheers.<br />JB

 

[andrewkafp]

Re: Good gas goes Bad?

If you are contstantly "topping up" or adding a couple of gallons (premixed) to your tank, how would this affect the mixture ?<br />I tend to run the tank down to half and then might not use for 4 weeks, refill to top with premix fresh fuel.<br />Is this a good practice ? or should I dump the half tank and start over ?

 

[andrewkafp]

Re: Good gas goes Bad?

bmp

 

[lakeman1999]

Re: Good gas goes Bad?

Andrews questions is a good one, my pontoon and fishing boat both stay in the water at the dock, and the tank never emties. I just keep adding premix, like our automobiles, so as to not run out on the water, as happened "ONE TIME" (both have permanent mounted large tanks). What happens to the fuel here?

 

[NOSLEEP]

Re: Good gas goes Bad?

mtp is right, gas deteriorates mush faster in hot<br />climates than it does in the cold. I have always<br />stored my boat with a full fuel tank for more than<br />seven months out of the year. My two stroke <br />evinrude always runs fine in the spring out of<br />storage. I have never added fuel stabilizer in any<br />of my motors,never needed too.The main reason is <br />its below freezing over the winter and the gas<br />doesn't go bad.

 

[andrewkafp]

Re: Good gas goes Bad?

I live in Southern Australia, where it is now winter. (ave about 12-20deg C). I don't get many chances to use the boat as the Bays are a bit choppy, but we never get down to freezing here.<br />My fuel is currently about 4 weeks old and already mixed for periodic running of motors but if I don't use the boat soon, I will most likely dump the fuel. In the summer, it will not sit around long I assure you.

 

[oldboat1]

Re: Good gas goes Bad?

I think I would add a stabilizer, but wait until spring/summer to make a decision on whether to dispose of the gas (need to keep the tank full through the winter anyway to prevent condensation, right?) If you have performance problems (poor running/idling, hard starting, etc.) when you get around to running the motor, though, I would switch to fresh gas before doing any more diagnostics. Chances are, the stabilizer will do the job, but I've been surprised by bad gas so I know it can happen.

 

[Forktail]

Re: Good gas goes Bad?

This might surprise you. It's from Chevron, the gasoline makers. <br /> <br />"Gasoline stored in a tightly closed container in a cool place will stay good for at least one year. It is better if the container or gas tank is almost (95%) full. If the container or gas tank will be in the direct sun or will be heated above 80°F much of the time, add an aftermarket fuel stabilizer to the gasoline when you first buy it. Gasoline-oil blends for two-stroke cycle engines stored under the proper conditions will keep as well as gasoline itself."<br /><br />And this is from Shell...<br /><br />"All gasolines have finite storage life. If storing gasoline longer than six months, you may want to use a supplemental fuel preservative additive.<br /><br />If aged long enough, gasolines can form gum and varnish that can cause engine operating problems, and sometimes to the engine and the fuel tank. All Shell gasolines - conventional and reformulated - meet ASTM requirements for stability (a measure of protection against oxidation that can degrade gasoline properties). How long gasoline can be stored depends mostly on storage conditions. Increased temperature, exposure to air and contaminants, and the material the storage container is made of can shorten storage life. Generally, gasoline stored for longer than 6 months will likely benefit from adding a supplemental stabilizing additive, usually available at your Shell service station. Store gasoline only in an approved container, well away from sources of ignition."

 

[andrewkafp]

Re: Good gas goes Bad?

I thought about this..<br /><br />Why aren't they telling us to throw it away after 6 weeks??? It would sell more gasoline ??<br />Because THEY store it for a year and longer and don't want a "can of worms" opened related to storage time.<br /><br />Geez I'm negatative.....

 

[NOSLEEP]

Re: Good gas goes Bad?

When you buy gas at the pump from a reputable<br />dealer you are good to for at least 6 mths in a warmer climate.

 

[NOSLEEP]

Re: Good gas goes Bad?

I wasn't finished typing. When gas evaporates it <br />leaves behind a small residue like varnish. thats<br />what plugs your jets. Add to that oil,and you have<br />a mixture when evaporated it can plugs things<br />up in the carb jets. But gasoline for the most<br />part is perfectly fine for more than 1 year.<br />From experience I can say I have run engines that<br />performed well with fuel more than 18 months old.

 

[andrewkafp]

Re: Good gas goes Bad?

NOSLEEP by name and nature ??? <br /><br />I have a excuse.. it's only 4:00 pm here <br /><br />I would say that storing the fuel in the boat tank and then adding oil when ready to use would be a fairly good practice then ??<br />For those with Oil injection.. it wouldn't matter as much.

 

[Forktail]

Re: Good gas goes Bad?

Couple of things...<br /><br />The oil doesn't make a difference for storage. per Chevron, "Gasoline-oil blends for two-stroke cycle engines stored under the proper conditions will keep as well as gasoline itself."<br /><br />Also, the newer technology fuels of today aren't as prone to "varnish" as the older fuels were. It would take some serious neglect and long, long periods of storage to form "varnish" in the fuel system.