I put some 100:1 amosil in my rider after running out during the job. I had it left over from a DA50 I sold and didn't have another motor at the time. It ran fine... of course 100:1 isn't a lot of oil anyways.

Originally Posted by Stainless Skills

I put some in a honda Lawnmower and it smoked like crazy for about 30 minutes. But all was fine after that.

What is this deal about not letting the mix sit for over 10 days. Does it only apply to castor or does it only apply to synthetic? I have never heard anything like it before. Does averyone do it or do only a few people even know about it? I have never heard anything from any rc engine company about it so is it not a big deal if you let the gas sit or what?

When I was racing MX I ran some of the most expensive synthetic 2 stroke oil on the market (It made a big difference). There was a huge difference in power from new gas to mixed gas that was over 5 days old. The minute the oil is added the mixture of gas and oil starts to break down. You can use gas over 10 days old but it is a bad idea. Old mixed gas eventually turns into varathane and gums up lines, needles, reeds etc. Considering how little gas airplanes use and the relatively cheap price, It seems worth while to buy new gas at least every 2 weekend to help protect your very expensive plane. Dump the unused gas into your vehicle.

Originally Posted by hillmanr2

When I was racing MX I ran some of the most expensive synthetic 2 stroke oil on the market (It made a big difference). There was a huge difference in power from new gas to mixed gas that was over 5 days old. The minute the oil is added the mixture of gas and oil starts to break down. You can use gas over 10 days old but it is a bad idea. Old mixed gas eventually turns into varathane and gums up lines, needles, reeds etc. Considering how little gas airplanes use and the relatively cheap price, It seems worth while to buy new gas at least every 2 weekend to help protect your very expensive plane. Dump the unused gas into your vehicle.

I mix 5 gallons at a time and it usually takes at least 3 weeks to a month to get through that. This is the first I've heard that over 10 days is bad. Anyone else have an opinion on this?

I would not do it. For those of you who say it will have no effect on sensors etc. Must not have driven a newer car in the northern climates. Both of my wifes last two cars a volvo cross country and a buick Rainer would all of a sudden start having the check engine light come on around mid november and it would come on and stay on periodically till mid may due to the winter blends of fuel used up here in CT. I certainly would think oil in the gas would do the same thing.

I've been running my lawnmower on pre mix for for the last six months without a problem, and I've run my 74 Jeep on it in an emergency.

I actually ran tank of 15% Coolpower in my mower a while back, I had to run it full throttle and it was a little smokey but I finished my lawn. It was tough on the rubber parts so I wouldn't recommend it

I DO IT EXCLUSIVELY AFTER EVENTS IT MAKES THE CAR FLY HOME !!!

Originally Posted by aviti

I mix 5 gallons at a time and it usually takes at least 3 weeks to a month to get through that. This is the first I've heard that over 10 days is bad. Anyone else have an opinion on this?

http://www.pcpros.net/~tvoss/techTip/200509.htm
"Some other helpful hints: If pre-mixing, only premix enough gas as for your immediate needs. Gas that sits for longer than 10 days will go stale causing greatly reduced engine performance and gumming and varnishing of engine components and fuel components. Always drain carburetor and fuel lines if the aircraft is going to sit for an extended period of time"

I have read this multiple times before from my MX days. This quote is more relivant as it applies to full scale avaition. The link is to the page it came from

Always wondered about pre-mix sitting around for a while... definetly some interesting info. Good thing I burn 3-5 gallons a week or more in the summer! No chance for it to go bad!!!

Did you bother to have the check engine light checked by a qualified tech? A scan by some kid at AutoZone doesn't cut it. All engines use oil and that oil gets mixed with the fuel in the combustion process. There are no sensors that actually touch the fuel. GM has for 40 years stated one quart of oil per 1,000 miles is "normal". Most engines will not come close to that but I see smoking engines all day long with no measureable performance difference.

While I might believe that running old mix in an engine might not give top performance, I'm not sure I agree that running something more than 10 days old will cause varnish and clog up a carb. I have used premix that is over 1 year old in my leaf blower and weedeaters routinely, and I've NEVER had to adjust the mixture. I won't go that long with my airplane engine, but I would not hesitate to use month old mix.

OTOH, gasoline by itself will go bad, it does not have to be mixed with oil. (In fact, I've read somewhere that some oils have stablizers, don't know if that is true or just marketing hype.) I have a camper with generator, and I have to exercise the generator every month and use fuel stablizer to keep the carb on the generator clean (don't ask me how I know!!!).

I'm no expert on auto engines, but from my limited knowledge I would be more worried about the catalytic converter than I would injectors. I would think 1 gallon of premix in a nearly full tank on an automobile would not be a problem, JMHO.

Bob R.

I guess I am being argumentative now but I don't understand why you would use fuel that will cause a lack of performance. I for one, try to spend the money on top of the line equipment to get the most out of my planes. Seems counter productive to cheap out on the one product that is relatively inexpensive but can cause such a dramatic difference.

Cheers

Originally Posted by hillmanr2

I guess I am being argumentative now but I don't understand why you would use fuel that will cause a lack of performance. I for one, try to spend the money on top of the line equipment to get the most out of my planes. Seems counter productive to cheap out on the one product that is relatively inexpensive but can cause such a dramatic difference.

I tend to agree. But, with month old mix I have not noticed a "dramatic difference". Do you have any empirical data you can share?

I guess I would feel diffferently if I was flying in competition, but for everyday sport flying I'm not worried that I might lose 100 rpms.

The next time I mix some fuel, I will try to take before/after rpm readings.

Bob R.

Originally Posted by Wrench

Did you bother to have the check engine light checked by a qualified tech? A scan by some kid at AutoZone doesn't cut it. All engines use oil and that oil gets mixed with the fuel in the combustion process. There are no sensors that actually touch the fuel. GM has for 40 years stated one quart of oil per 1,000 miles is "normal". Most engines will not come close to that but I see smoking engines all day long with no measureable performance difference.

Well, I am a qualified tech, and I disagree with putting a 2 stroke mix in any vehicle. For one, rubber and oil do not mix. The oil will cause the rubber to swell. Yes the fuel injectors have rubber parts that the fuel does pass through. This is before it gets to the combustion chamber. So yes it can cause damage to your engine. Use your old 2 stroke mix to start a bon fire, not to run you car engine. This could be very costly for you. Then when you take it to the dealer and they find out you had contaminated fuel, they will void your warranty. Don't do it.

A quart of oil per 1,000 miles is not normal. If you have an engine that holds 5 quarts of oil and you change it every 3,000 miles that only gives you 2 quarts of oil remaining when you change the oil. NOT GOOD. Now let's say you drive your vehicle 7,500 miles before you change the oil, as GM states you can do with there newer vehicles. If you are burning 1 quart of oil per 1,000 miles that would mean, that at 5,000 miles you would not have any oil left, and you are going to drive another 2,500 miles.

So, what does all of this mean? Only mix up enough 2 stroke fuel to meet your needs. I never mix more than 2.5 gallons at a time. I have a 5 gallon jug full of fuel that I use to fill my 2.5 gallon mixed jug. Some people may only need one gallon, while others could burn 5 gallons in a weekend. Don't put left over fuel in your car, you will save yourself a ton of money and grief. Besides, what if the problems that can and will happen decide to show their ugly head when you are on your way to an event 500 miles from home. That would just suck.

Mike Darr

Mike Darr

Originally Posted by Wrench

Did you bother to have the check engine light checked by a qualified tech? A scan by some kid at AutoZone doesn't cut it. All engines use oil and that oil gets mixed with the fuel in the combustion process. There are no sensors that actually touch the fuel. GM has for 40 years stated one quart of oil per 1,000 miles is "normal". Most engines will not come close to that but I see smoking engines all day long with no measureable performance difference.

Yes both cars this happend to went back to the original dealer they cars were purchased from. On the GM it went back 2 times the second time was when I got the winter fuel answer. Never saw a difference in performance or milage from when the engine light was on to when it was off. However running a higher octane on the GM seemed to make it happen less often.

On the Volvo it was back to the dealer several times for this issue I was told on the volvo there are 30+ sensore that run the emisions sytem. Monitoring everything from intake air temp, volume, rate of flow etc... and tmany things on the fuel instake as well. They also monitor the exhuast gas , for varouse things as well. It is a combination of all those sensors that keep the emision gasses low. One odd thing in the set up can set the whole thing out of wack. Even from something as simple as the wrong gas cap vented or not vented.

Here is what does not make sense to me. I can understand not wanting to run questionable fuel in your 1500.00+ airplane motor. So when did it make sence to put it into your 25,000.00+ car ?? What's the logic there? I for one run it into my 100.00 weed wacker and never had a problem with it.

Originally Posted by bryan01601

Here is what does not make sense to me. I can understand not wanting to run questionable fuel in your 1500.00+ airplane motor. So when did it make sence to put it into your 25,000.00+ car ?? What's the logic there? I for one run it into my 100.00 weed wacker and never had a problem with it.

Can't argue with that!!!!