Champstarr

Hi Everyone,

How long can I keep my two stroke gas before I need to toss it? I use Ethanol Free unleaded gas, synthetic two stroke engine oil with a 32:1 ratio for my VVRC 20cc engine in my TF .60 p47. I store it in a Jersey Modeler fueling can which is well sealed and I store it out of the sunlight.

I have done a search for this topic on many different forums and the results range from two weeks to a full year. I hoping the specifics I gave about my situation will define the answers a little better.

Thanks,

ahicks

My Feedback: (2)

My experience has been that once gas, any gas, is mixed with a quality oil, it's safe for at least a year. Not that I would encourage people to mix up so much at a time that it would last that long, but I've had no problem when "stuff happens" and it ends up being that long.

Champstarr

The gas I am using is mixed with MOTUL 100% synthetic racing oil.

Champstarr

The fuel in question is about two months old now. Last weekend the engine fired right up with no problem could that be an indicator of the fuel quality?

ahicks

My Feedback: (2)

No point in looking for trouble. If it ran fine, I'm struggling to see a downside from finishing it off.

Champstarr

Great, I'll use it all. Thanks for the input

Truckracer

My Feedback: (19)

"The nose knows"! Not that you should go around sniffing gasoline but stale gas will have a distinct odor different than fresh gas. Many times just sniffing the suspect fuel will tell you if it is time for it to go away. I have a separate fuel jug for "suspect" airplane gas. Anytime I suspect the fuel might be getting a bit old it gets tossed to the suspect jug for use in my string trimmer, chainsaw, etc. And I've never had a problem with the leftover fuels causing a problem in these other machines.

GSXR1000

My Feedback: (7)

+1 my skunky rc gas goes into the 2 stroke weedeater/chainsaw gas jug...

Zeeb

My Feedback: (41)

To me, it seems to smell like varnish when it gets really old. I always use a fuel preserver when I fill my Jerry can at the gas station and that's what I use for my models and yard tools. I don't keep a lot of it around but I do not recall it getting stinky in the can. I have had the stuff go bad in my pressure washer and that was a pain to deal with....

ahicks

My Feedback: (2)

Just me, but if the gas doesn't smell right, it's going to the recycler. I wouldn't put that in anything. That's just asking for trouble....

captinjohn

Use Pure gas, it will last a year with no problem. http://www.pure-gas.org/ It is the best...look no further.

vertical grimmace

My Feedback: (1)

Funny, I was just about to start a thread about this issue.

Getting mad at the RC hobby, I have not been flying it for the last year and a half. I had a gallon which was about 3/4 full. I flew once earlier in the summer, and my engine ran OK, but it did not seem to have the power it should have.

Well, I was going through my fleet of WW1 birds a week ago to prepare them for a warbird meet tomorrow. Sure enough, the trusty old DLE 55 was sputtering and hesitating big time. It started and idled OK, but the mid range was terrible, and it could barely be nursed to full throttle. So I got rid of that gas, and got a fresh gallon. Guess what? It runs perfect now!

So after this experience, and my previous experiences of not using my gas through the winter months, I would say 9 mo. to a year and it is done. I have thrown in fuel stabalizer before, but I have heard mixed opinions about that stuff, so do not use it. The oil I use is Stihl Ultra at 32-1.

Zeeb

My Feedback: (41)

The Stihl two cycle oils have a fuel stabilizer already mixed into the oil. That's one of the reasons I use Stihl in my two stroke engines.

flyinwalenda

My Feedback: (5)

If you are using "pump gas" the 2-stroke mix will only last 2 months or so.
If you use "AV Gas" the 2-stroke mix will last over a year.

J330

My Feedback: (3)

Thankfully gas is cheap enough now, helps make better decisions to be cautious, than when deciding what to do when gas was $4.25 / gallon. I bought a motorcycle to save gas in 2011. Now I can't get rid of it. Truck prices are going sky high. Naturally, we can now also throw the stuff away when it's questionable.

SkidMan

My Feedback: (17)

Due to the closure of the local field that allowed fuel aircraft, I had some gas that was well over a year old.

Keep in mind that it was ethanol free and mixed with Stihl Ultra HP, but it still runs just fine.

vertical grimmace

My Feedback: (1)

Yeah, I guess if there is ethanol in the gas, like the stuff sold here in CO, it will pull moisture (water) out of the air. So there is a good possibility that water can be present in gas that sits around with ethanol. Not to mention, my fueling can is not sealed up 100% because of my fuel line fitting.

prigai

Instead of using it in your 2 stroke weedeater/chainsaw add it to your 4 stroke lawnmower gas tank at up to 10% ratio (or to your gas car at up to 5% ratio).
Not knowing the quality of the old gas, up to 10% mix will not degrade the quality of the gas in the tank but will add a bit of 2 stroke oil (around 0.3%) which will assist top end lubrication and over time help clean the valves and combustion chamber. I always keep a fresh mix for my RC engines and 2 stroke yard equipment, if I don't have an old mix to use in my lawnmower I use a bit of the fresh mix.

Champstarr

Even if it's ethanol free?

flyinwalenda

My Feedback: (5)

Well ethanol-free .may prolong it a bit ,but not like av-gas.

Champstarr

Just wanted to give an update. I flew my P47 this weekend. On the first flight the engine started sputtering at full throttle. After the flight I noticed there was a crack in the prop. I replaced it at the field and flew several more times with no problems. I suppose the cracked prop cause excessive vibration and the fuel to foam which gave me a sometimes sputtering engine.

Bottom line is the fuel was fine.

Thanks for all the input.

av8tor1977

My Feedback: (6)

The oil degrades the octane, especially over time. The alcohol in the fuel attracts moisture. The aromatics , which help starting, fuel atomization, etc., evaporate. I don't care how many stories you hear about one year old fuel "working just fine". You have a serious investment in time, money, and love in your airplane. Spend three bucks and run it on fresh fuel.

When I attended the Rotax School for Authorized Service Centers, they taught us to avoid using fuel mixed with oil that was more than two weeks old, and absolutely never, ever to use any that was a month or more old. They have just a bit more experience with two stroke engines all over the planet than most of us do.......

AV8TOR

ahicks

My Feedback: (2)

Thinking that Rotax school info, when speaking of today's oils/fuels, is badly outdated

Champstarr

See this is what I mean. I hear anywhere from two weeks to a year. Like I mentioned in my previous post. The fuel did work fine after having it for a little over two months. The engine started up right away and performed well at all throttle settings. From other posts as I understand it the lighter elements of the fuel evaporate first making the engine more difficult to start. The engine had no probs starting so this would leave me believe the degradation of the fuel so minute it virtually had no impact on the operating quality of the engine.

Zeeb

My Feedback: (41)

I agree with ahicks on this one. The other issue that some suggestions for solving have been offered, no one has really addressed how you dispose of old gasoline should you decide that two week old gas isn't usable?