Does gas/oil mix go bad after a while?


14 replies to this topic
  • kpmnc24

Posted 23 January 2006 - 11:58 AM

#1

I know most people say to mix the gas and oil right before you use it if possible, but I am wondering if it will degrade (or does the gas and oil separate?) if you let it sit in your bike for a while?

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  • motox262000

Posted 23 January 2006 - 01:46 PM

#2

After a while it will. A lot of guys only mix what they run for the day. I usually mix 5 gallons at a time, and even let it sit for a few weeks before using it sometimes wihtout any trouble. I wouldn't let it sit all winter tho, at least put some fuel stabilizer in it.

  • killerdwarf77

Posted 23 January 2006 - 03:27 PM

#3

Yes, it most definetly will! Gasoline loses volitility, oil will seperate, and also will possibly attract some moisture. If you have a habit of leaving the fuel in your bikes tank for a couple of weeks or even a month between rides, do you and your bike a favour and use a fresh mix. You do not need to fill your jerry can up, buy and mix only as much as you need for maybe 2 wknds. worth of riding. A properly sealing fuel container will store the fuel fine. When you are done your riding for the week, drain your tank back into your jerry can, your bikes fuel tank is vented and does not store fuel well.

  • JMC

Posted 23 January 2006 - 05:55 PM

#4

I don't like to run old gas in my bikes but I have. I mix up fresh as much as possible and save the old stuff for my snowblowers and other lawn equip. Some as old as a year! In a pinch I have run similar in my bikes. I remember a bike magizine talked about this issue some time ago and said something like- we have run gas that was up to 6+ months old w/no ill effects but we would not recommend it according to man. guidelines. I have never had any problems w/any of my bikes or equipment. I do run syn. premix all the time, maybe that helps. I will dump the old stuff in my 1955 tractor if it has set all winter as long as I have $$$ for fresh. LOL.

  • dfcfu342

Posted 23 January 2006 - 06:56 PM

#5

The magic number for BEST performance is 30 days. But, with stabilizer you can go a few months. Remember that oil is made from the same stuff gas is. It will too go bad after a while.

  • killerdwarf77

Posted 23 January 2006 - 07:31 PM

#6

I have read somewhere, maybe even on the label of stabilizer, I don't remember, that it is not to be used in high perf. 2stroke engines. Our 2stroke dirtbikes are pretty finiky on fuel, they don't seem to get along with some additives, and even some types of gasoline too well. :thumbsup:

  • CRFan1

Posted 24 January 2006 - 08:26 AM

#7

I don't know, I use 100 octane and HP2 in my bike.....I am sure that it would be fine sitting for quite a while. Plus, my garage never really gets too terribly cold (insulated.....I am in Northwest Indiana). I keep mine fueled up because this time of year, if the weather gets nice, we go - like maybe this Sunday....supposed to be 48! :thumbsup:

  • Silver Surfer

Posted 24 January 2006 - 09:19 AM

#8

it will go bad.

oil will NOT seperate from gas. <-- thats a period

  • Mike_Lettrich

Posted 24 January 2006 - 10:03 AM

#9

it will go bad.

oil will NOT seperate from gas. <-- thats a period


Exactly. Gasoline is a mixture of hydrocarbons. Over time, the lighter elements in the gasoline will evaporate, deteriorating its performance. These elements will evaporate even through a plastic container. The oil will not separate from the gas.

Mix only what you expect to use in the next couple of weeks. If you have some left over, you can burn it in your two stroke lawnmower or weed whacker.

  • rdefonce

Posted 24 January 2006 - 10:13 AM

#10

Exactly. Gasoline is a mixture of hydrocarbons. Over time, the lighter elements in the gasoline will evaporate, deteriorating its performance. These elements will evaporate even through a plastic container. The oil will not separate from the gas.

Mix only what you expect to use in the next couple of weeks. If you have some left over, you can burn it in your two stroke lawnmower or weed whacker.


Mike, I generally try not to run old gas but I use StaBil fuel stabilizer if bike's gonna sit for a month or two. This seems to work just fine and bikes run great even with 2 month-old gas.

I wouldn't recommend this; a friend left a tank of Golden Spectro pre-mix in his 430 Husky for almost 2 years. It started in 3 kicks and ran fine :thumbsup:

Of course, "running fine" doesn't mean it ran as good as with fresh gas!

  • jbroom

Posted 24 January 2006 - 03:36 PM

#11

i race a 2 stroke 50 road bike. i try to only fill up the can with as much as i need for a weekend and mix it the morning before the race. after the weekend i drain my tank back into my can and pour whatever is left into my truck one gallon at a time with a full tank of gas until it's empty. that way i can start fresh for the next race.

  • NorCal

Posted 25 January 2006 - 02:21 PM

#12

i race a 2 stroke 50 road bike. i try to only fill up the can with as much as i need for a weekend and mix it the morning before the race. after the weekend i drain my tank back into my can and pour whatever is left into my truck one gallon at a time with a full tank of gas until it's empty. that way i can start fresh for the next race.




I dumped about 3-4 gallons of mixed fuel into my truck on accident. :bonk: I didn't notice any difference when driving it. Could this hurt my engine? :thumbsup: Oh, its a toyota 3.0 V6.... if that makes any difference

  • Silver Surfer

Posted 25 January 2006 - 02:23 PM

#13

notice any oil spots on the windshield of the guy behind you~!
LOL

  • killerdwarf77

Posted 25 January 2006 - 03:39 PM

#14

keep diluting the fuel by filling up often, you could possibly damage your convertor

  • jbroom

Posted 25 January 2006 - 04:14 PM

#15

3-4 gallons with lots of oil probably isnt' that good... but a gallon or 2 of 32:1 to a 15 gallon tank shouldn't matter.





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