Old Gas vs New Gas?

[Biketrax]

On a recent post someone mentioned not to use gas over a few months old?
Well what kind of damage can we do? TO Small engines vs larger ones? Snow blower, lawn mower, weed wacker some chainsaws... what do you do beside put some stabilizer? I usually refresh the old batch by topping it off with a new mixture.
I can't be emptying out all these if they sit for over 2-3 months? OR DO I?
Whats your take ?
Does octane make any big difference?

 

[Mike mandry]

I only mix mine in quarts as needed unless I am cutting a lot.

I have a 2.5 gal can of 93 that I keep on hand. After 4 weeks, it goes in the car or van when I fill them up. No waste & I always have fresh fuel.

I live in the boonies & for the time being, we have ethanol free fuel. At least that is what I have been told...........

 

[fast*st]

I may be out in the woods here myself, I've not dismantled a chainsaw carb to inspect what having some aged new gas in it does but I have a little experience with another engine, motorcycle engines.

The new gas with ethanol seems to cause something interesting when its left to sit in the fuel bowls, the brass jets gather a green clay / gum like substance that seems to be a mix of corrosion and varnish? Solvents don't seem to bother this sludge, wire brushing helps, I'm going to try an experiment with an alcohol/acetic acid mix to see of that works.

Most of the quality 2 stroke mix already includes a fuel stabilizer in it, I'm not sure if that will prevent or reduce this new buildup. Skip adding drygas, a car fillup already will have 1.5 - 2 gallons pre mixed

I've worked on bike carbs for friends for more than a few years, but this crud is new on the ballfield.

-Jason

 

[bump_r]

http://www.straightdope.com/columns/060825.html

 

[CrazyCarl]

old gas

I too have experience with carb's on motorcycles and other machines,and I have run into some problems with gas mix older than 4 month's.especially ethenol.Seem's to leave a much more corrosive deposit in the bowl area.I have used acetone to dilute this coating with good results.Just be careful to rinse the part well.After 3 month's,I do the same,dump it in my riding mower(10 gallon tank) and use no more than a gallon per full tank.If I have more than i can burn off in one cutting then i give it to the local farmers to burn off what ever they need.(Brush,over grown grass,etc etc).I live in a small town so we do a lot of trading services.Most folk around here bring their small engine work to me.Not saying I'm the best,but I am honest and back up my work.And I'm cheap!!!!!!!Some times trading one knowledge for another

 

[fishhuntcutwood]

Well what kind of damage can we do?

You can ruin your engine. I only keep gas for a month or two. Dump your old two stroke gas in your truck's gas tank. It'll burn it fine. What's the couple of bucks compared to a $900 saw? Don't cut corners with gas. I don't trust Stabil either. It may work fine, but why mess with it? Just dump your gas and buy a couple of fresh gallons next time around.

 

[TimberPig]

The two biggest issues with old gas are in the carbs and fuel system, and in the reduced octane and miscibility of the oil in the fuel mix.

The plugged carbs, and rotten fuel lines have already been well covered, so I won't go any further on that.

The reduced octane and the tendency of the oil to not remain correctly mixed in older fuel are the larger concern in 2 stroke engines. Lower octane leads to issues such as detonation and can cause burned down engines in 2 strokes. Four strokes are much more tolerant, as they tend to be less highly tuned, so old fuel with reduced octane and volatility is less of a problem.

Since 2 strokes use oil/fuel mix to lube the crankcase and piston/cylinder, the reduction of oil in the mix that reaches the cylinder can lead to lubrication breakdowns, which leads to seized bearings and burnt top ends. Again, since 4 strokes are lubed by a crankcase full of oil, this isn't an issue there.

As you can easily see, the hassle and potential for damage isn't worth risking it to avoid dumping out and using up old gas, particularly for your 2 strokes. I know I'd rather dump gas out of a saw, than rebuild it because the carb was plugged and the fuel mix was almost straight gas

 

[gasman]

Gas companies are required to post if ethanol is in the gasoline. But the sticker can be fairly small or hidden. No one mentioned that ethanol has higher water content and that alone may be an issue in a motor. I think in reality most people don't worry about gas for 3 months but FHCW gives an easy solution to keep fresh gas. He clearly has high standards for his saws. I do the same if I have gas for longer than 3 months which I rarely do.

 

[ehgauss]

Old gas

Years ago, I used to dispose of aging mixed gas by pouring into the gas tank of my '76 pickup being careful to dilute it well, adding only a little at a time. It worked fine. However, the first time I did it with a car with more modern pollution controls, an '89. the gas mileage dropped dramatically, and the oxygen sensor plugged up. I not saying that was the cause, but I don't do that anymore. I use it in a '52 tractor instead. Gene Gauss