Questions for the fuel experts

[Old2stroke]

--Why does gasoline (ethanol free) deteriorate with time and does storage in a sealed container help slow down the process?
--Does modern gasoline deteriorate faster than, say, 20 years ago?
--Does "summer" gas go bad faster than "winter" gas, or vice versa?
--As fuel ages, does the octane rating go down?
--How can we tell if a fuel stabilizer is a good product or just junk in a bottle?
--Given a fuel containing 100cc of ethanol, how much water would it take to absorb all the alcohol? We are now not able to buy alcohol free gas in Ontario.
We all tend to caution others to only use fresh fuel, some would have us believe 3 months is the best before date. I have no problems with 6 month old fuel, are we being too conservative?

 

[bwalker]

Yes, it still deteriorates in sealed containers. Gas goes bad in two different ways. It's loses volatility and it forms varnish. Sealed metal containers prevent a loss in volatility and inhibit, but do not prevent the formation of varnish.
Winter gas is more high volatile to help engines start and run right in the winter thus it has more to lose before it goes flat. Summer fuel goes flat faster. Both form varnish at about the same rate. Winter fuel when used this time of year vaporlocks much easier, which is often blamed on bad gas, but that isn't so.
As fuel ages it does lose octane. Partly because certain light end streams are high in octane and when they evaporate you lose octane. Also some of the heavier streams break down they also lose octane.
Stabil for sure helps, but not to the degree guys think. Refineries have already added concentrated stabil to their gas. Adding a little more helps, but given the law of diminishing returns its not a cure all. Same story for double dosing with Stabil. Stabil will also not prevent volatility loss.
I am not sure what the saturation point of ethanol is.
In reference to your last question. It's nearly impossible to say. Gas is a chemical soup whose blend changes daily. Premium fuel has a higher percentage of alkylate/platformate blended into it so it will typicaly last longer. That said it may go bad in a few months or it might last for a year or more.
Ethanol blended fuel goes bad much faster and beyond that causes issues even when it's not bad. It absorbs water from the air through the walls of your tank and while sitting in your carb. I woukd absolutely not store any gas with ethanol in it nore would I alow it to sit in my power equipment long term with the use of stabil or not.

 

[Old2stroke]

Yes, it still deteriorates in sealed containers. Gas goes bad in two different ways. It's loses volatility and it forms varnish. Sealed metal containers prevent a loss in volatility and inhibit, but do not prevent the formation of varnish.
Winter gas is more high volatile to help engines start and run right in the winter thus it has more to lose before it goes flat. Summer fuel goes flat faster. Both form varnish at about the same rate. Winter fuel when used this time of year vaporlocks much easier, which is often blamed on bad gas, but that isn't so.
As fuel ages it does lose octane. Partly because certain light end streams are high in octane and when they evaporate you lose octane. Also some of the heavier streams break down they also lose octane.
Stabil for sure helps, but not to the degree guys think. Refineries have already added concentrated stabil to their gas. Adding a little more helps, but given the law of diminishing returns its not a cure all. Same story for double dosing with Stabil. Stabil will also not prevent volatility loss.
I am not sure what the saturation point of ethanol is.
In reference to your last question. It's nearly impossible to say. Gas is a chemical soup whose blend changes daily. Premium fuel has a higher percentage of alkylate/platformate blended into it so it will typicaly last longer. That said it may go bad in a few months or it might last for a year or more.
Ethanol blended fuel goes bad much faster and beyond that causes issues even when it's not bad. It absorbs water from the air through the walls of your tank and while sitting in your carb. I woukd absolutely not store any gas with ethanol in it nore would I alow it to sit in my power equipment long term with the use of stabil or not.

Thanks a lot for the info. Good to know.

 

[OM617YOTA]

Fuel life seems to be area dependent too. What works in your area may not work in someone else's, and just because someone else can get away with something in their area, doesn't mean you will in your area. Different weather, temperature range, humidity, specific fuel blend for your area, how you hold your tongue while you're pumping gas into your fuel can, etc.

 

[holeycow]

It's a major pain in the ass.

 

[bwalker]

Fuel life seems to be area dependent too. What works in your area may not work in someone else's, and just because someone else can get away with something in their area, doesn't mean you will in your area. Different weather, temperature range, humidity, specific fuel blend for your area, how you hold your tongue while you're pumping gas into your fuel can, etc.

High temp and high humidity both hamper storage.

 

[Hermio]

--Why does gasoline (ethanol free) deteriorate with time and does storage in a sealed container help slow down the process?
--Does modern gasoline deteriorate faster than, say, 20 years ago?
--Does "summer" gas go bad faster than "winter" gas, or vice versa?
--As fuel ages, does the octane rating go down?
--How can we tell if a fuel stabilizer is a good product or just junk in a bottle?
--Given a fuel containing 100cc of ethanol, how much water would it take to absorb all the alcohol? We are now not able to buy alcohol free gas in Ontario.
We all tend to caution others to only use fresh fuel, some would have us believe 3 months is the best before date. I have no problems with 6 month old fuel, are we being too conservative?

I have used Sta-bil for many years. The gas is still usable after 2 years when kept in a reasonably sealed container. Bwalker below is right when he says the more volatile fractions will evaporate when not in a sealed container. Stabil will not prevent that. But another way gas goes bad is by oxidation. Stabil seems to help with that, and to help keep ethanol/water mixtures from separating. It is probably best to use ethanol-free gas, but it is often unavailable locally. I have used E10 gas with Stabil for decades, and have not had fuel problems except when left in a string trimmer for more than 2 years. The string trimmer fuel tank is not really a sealed container.

 

[bwalker]

I have used Sta-bil for many years. The gas is still usable after 2 years when kept in a reasonably sealed container. Bwalker below is right when he says the more volatile fractions will evaporate when not in a sealed container. Stabil will not prevent that. But another way gas goes bad is by oxidation. Stabil seems to help with that, and to help keep ethanol/water mixtures from separating. It is probably best to use ethanol-free gas, but it is often unavailable locally. I have used E10 gas with Stabil for decades, and have not had fuel problems except when left in a string trimmer for more than 2 years. The string trimmer fuel tank is not really a sealed container.

Plastic containers are not suited for long term storage. The plastic is porus and allows water vapor to enter and light ends to leave.

 

[NSEric]

I have a atv and motor bikes so I always have a jug of gas in the garage.
I only mix up one gallon(4 liters to be exact) of gas for the chainsaws at a time out of the jug of gas I already have.
If either gas jug gets more than a month old, it goes into the cars gas tank when the car is more than half full.
Since I started doing this I havent had any gas related issues and I buy regular half the time lol.
Im being overly cautious doing this but all it cost me is a little mixing oil if I end up dumping a little mixed gas in the car.

 

[Cliff R]

This new fuel tends to evaporate faster but it doesn't leave behind "varnish" like earlier recipes did. At least not as much of it. What it does do if there is any ethanol in it is form "apple jelly" instead as it absorbs moisture in a vented system.

Stabil or other fuel additives do NOT protect you nearly as much as they advertise and will NOT prevent drying up, formation of "apple jelly", loss of octane, etc. I worked on small power equipment as a sideline to my carburetor restoration/rebuilding shop for over 20 years. I absolutely LOVE the fact that folks put Stabil in their fuel then let their chainsaws, string trimmers, leaf blowers, standby generators, power washers and other small power equipment set for many months and even years with gas in them and expect them to fire right up when they are called on.......in almost all cases that is NOT happening.

Here is a real World example from just a few years ago, to let folks know how this works. A very good friend of mine bought standby generator the last time a huge storm system moved thru here and flattened everything and we were over a week without power. It was a Honda powered 3500 watt unit. Three years later he calls on it again and it will NOT start. He brings it over and to my surprise the carb is clean (that engine had an auto shut-off on it so the carb just dried up but no fuel from the tank getting to it) unlike 99 percent of all the other ones I take in where the carb is clogged all up. Anyhow I dumped the tank into the gravel driveway outside the shop, cleaned it out, put in fresh fuel and it fired right up.

After he left I went out to burn the 3 gallons of fuel I just dumped in the driveway and it would NOT light. Yep, I lit a paper towel, tossed it on the fuel and ran for my life....NOTHING. Typically youd be lucky if you didn't get the hair singed off your arm and maybe even your eyebrows shorted up a bit if you didn't move quick enough, but this fuel would NOT burn. Eventually I was able to get it going but it took a torch and it started really slow then after a few minutes turned into an inferno much like I'd poured 3 gallons of diesel in the driveway, not gasoline.

Moral of the story, if it woln't burn at all in three years with Stabil in it, most likely it wasn't much good after 6-8 months of sitting, but that's just a guess on my part. In any and all cases it is best to remove ALL the fuel from your equipment for long term storage, even if it's seasonal. I also go to the extra effort here of running them till they stall out and pull the choke just as the engine dies out. Been doing that here for decades now and ZERO issues with any of my own equipment........

 

[stihltech]

Use your fuel up by 90 days. Problem solved (unless the water came from the pump. Seeing way too much of that lately, even in non ethanol.)

 

[lone wolf]

Use your fuel up by 90 days. Problem solved (unless the water came from the pump. Seeing way too much of that lately, even in non ethanol.)

Not so easy if you have trucks, cars, machines, saws, blowers, trimmers, log splitter etc.! Maybe 30–40 of them total! In fact, you can't keep up, it would be a full-time job. What do I do with 10 or 15 gallons of water -gas that came from just one truck?

 

[OM617YOTA]

Use your fuel up by 90 days. Problem solved (unless the water came from the pump. Seeing way too much of that lately, even in non ethanol.)

No surprise, water that would be absorbed by ethanol fuel, and carried through the system to be burned, collects at the bottom of non ethanol fuel tanks. Easy to get a slug of water if not careful.

 

[Hermio]

This new fuel tends to evaporate faster but it doesn't leave behind "varnish" like earlier recipes did. At least not as much of it. What it does do if there is any ethanol in it is form "apple jelly" instead as it absorbs moisture in a vented system.

Stabil or other fuel additives do NOT protect you nearly as much as they advertise and will NOT prevent drying up, formation of "apple jelly", loss of octane, etc. I worked on small power equipment as a sideline to my carburetor restoration/rebuilding shop for over 20 years. I absolutely LOVE the fact that folks put Stabil in their fuel then let their chainsaws, string trimmers, leaf blowers, standby generators, power washers and other small power equipment set for many months and even years with gas in them and expect them to fire right up when they are called on.......in almost all cases that is NOT happening.

Here is a real World example from just a few years ago, to let folks know how this works. A very good friend of mine bought standby generator the last time a huge storm system moved thru here and flattened everything and we were over a week without power. It was a Honda powered 3500 watt unit. Three years later he calls on it again and it will NOT start. He brings it over and to my surprise the carb is clean (that engine had an auto shut-off on it so the carb just dried up but no fuel from the tank getting to it) unlike 99 percent of all the other ones I take in where the carb is clogged all up. Anyhow I dumped the tank into the gravel driveway outside the shop, cleaned it out, put in fresh fuel and it fired right up.

After he left I went out to burn the 3 gallons of fuel I just dumped in the driveway and it would NOT light. Yep, I lit a paper towel, tossed it on the fuel and ran for my life....NOTHING. Typically youd be lucky if you didn't get the hair singed off your arm and maybe even your eyebrows shorted up a bit if you didn't move quick enough, but this fuel would NOT burn. Eventually I was able to get it going but it took a torch and it started really slow then after a few minutes turned into an inferno much like I'd poured 3 gallons of diesel in the driveway, not gasoline.

Moral of the story, if it woln't burn at all in three years with Stabil in it, most likely it wasn't much good after 6-8 months of sitting, but that's just a guess on my part. In any and all cases it is best to remove ALL the fuel from your equipment for long term storage, even if it's seasonal. I also go to the extra effort here of running them till they stall out and pull the choke just as the engine dies out. Been doing that here for decades now and ZERO issues with any of my own equipment........

Sta-bil will not prevent evaporation of the more volatile components, so a well-sealed container is still a necessity. With a sealed container, I have no problem with storing fuel for 1 year or more with Sta-bil, as it prevents oxidation and separation of ethanol. I have not tried to go two years.

 

[bwalker]

I have a atv and motor bikes so I always have a jug of gas in the garage.
I only mix up one gallon(4 liters to be exact) of gas for the chainsaws at a time out of the jug of gas I already have.
If either gas jug gets more than a month old, it goes into the cars gas tank when the car is more than half full.
Since I started doing this I havent had any gas related issues and I buy regular half the time lol.
Im being overly cautious doing this but all it cost me is a little mixing oil if I end up dumping a little mixed gas in the car.

I don't think your being over cautious. Just smart.

 

[bwalker]

No surprise, water that would be absorbed by ethanol fuel, and carried through the system to be burned, collects at the bottom of non ethanol fuel tanks. Easy to get a slug of water if not careful.

Ethanol will pull it out of the air. All that water found in storage tanks doesn't come from the fuel itself.

 

[Seachaser]

Not so easy if you have trucks, cars, machines, saws, blowers, trimmers, log splitter etc.! Maybe 30–40 of them total! In fact, you can't keep up, it would be a full-time job. What do I do with 10 or 15 gallons of water -gas that came from just one truck?

I agree. Bad gas is bad gas, but I’ve ran a lot that’s over two years old with no problems. All non ethanol of course. Most of the myths are overblown.

 

[bwalker]

This new fuel tends to evaporate faster but it doesn't leave behind "varnish" like earlier recipes did. At least not as much of it. What it does do if there is any ethanol in it is form "apple jelly" instead as it absorbs moisture in a vented system.

Stabil or other fuel additives do NOT protect you nearly as much as they advertise and will NOT prevent drying up, formation of "apple jelly", loss of octane, etc. I worked on small power equipment as a sideline to my carburetor restoration/rebuilding shop for over 20 years. I absolutely LOVE the fact that folks put Stabil in their fuel then let their chainsaws, string trimmers, leaf blowers, standby generators, power washers and other small power equipment set for many months and even years with gas in them and expect them to fire right up when they are called on.......in almost all cases that is NOT happening.

Here is a real World example from just a few years ago, to let folks know how this works. A very good friend of mine bought standby generator the last time a huge storm system moved thru here and flattened everything and we were over a week without power. It was a Honda powered 3500 watt unit. Three years later he calls on it again and it will NOT start. He brings it over and to my surprise the carb is clean (that engine had an auto shut-off on it so the carb just dried up but no fuel from the tank getting to it) unlike 99 percent of all the other ones I take in where the carb is clogged all up. Anyhow I dumped the tank into the gravel driveway outside the shop, cleaned it out, put in fresh fuel and it fired right up.

After he left I went out to burn the 3 gallons of fuel I just dumped in the driveway and it would NOT light. Yep, I lit a paper towel, tossed it on the fuel and ran for my life....NOTHING. Typically youd be lucky if you didn't get the hair singed off your arm and maybe even your eyebrows shorted up a bit if you didn't move quick enough, but this fuel would NOT burn. Eventually I was able to get it going but it took a torch and it started really slow then after a few minutes turned into an inferno much like I'd poured 3 gallons of diesel in the driveway, not gasoline.

Moral of the story, if it woln't burn at all in three years with Stabil in it, most likely it wasn't much good after 6-8 months of sitting, but that's just a guess on my part. In any and all cases it is best to remove ALL the fuel from your equipment for long term storage, even if it's seasonal. I also go to the extra effort here of running them till they stall out and pull the choke just as the engine dies out. Been doing that here for decades now and ZERO issues with any of my own equipment........

New fuel is less volatile than the older stuff. It's all about evaporative emmissions. And high volatility components are really a good thing in regards to a two cycle as it pertains to starting.
Your comments on Stabil overstatingbits effects are spot on. The refinery unit I work in produces a gasoline range stream that is 89-90 RON octane, but thatbis very unstable. As a result we blend in a industrial strength Stabil like product with it as it goes to blending. Fuel stabilizers have a fairly narrow range where they are effective. In other words if 2 ounces per gallon is adequate, 5 ounces won't do anything more.
I think it's a really bad idea to store gasoline, period. For starters it's a fire Hazzard and no matter what you do it's degraded.
For things like emergency generators where you have to store fuel I would go with propane or if I had to use gasoline I would use 100LL aviation fuel.

 

[OM617YOTA]

Sta-bil will not prevent evaporation of the more volatile components, so a well-sealed container is still a necessity. With a sealed container, I have no problem with storing fuel for 1 year or more with Sta-bil, as it prevents oxidation and separation of ethanol. I have not tried to go two years.

You wouldn't get away with that here. Ethanol fuel smells like sour milk in a year.

Ethanol will pull it out of the air. All that water found in storage tanks doesn't come from the fuel itself.

Very aware that the water comes from the atmosphere, not the fuel. Just talking about how the different fuels handle the water once it's there.

 

[Cliff R]

Here is my "system" for power equipment, both Quads, side by side, and all my smaller power equipement.

If it's a 4 stroke deal and doesn't have one a fuel shut-off valve is installed. So my log splitter, standby generator, power washer, both quads (carbureted) have shut-offs on them. When I'm done using them I shut the fuel to the carb, and just as they die out I pull the choke. All of them dating back decades have ZERO issues with getting plugged up.

For small 2 stroke equipment, leaf blowers (3), chainsaws (about a dozen), string trimmers (2), pole saw (1), garden tiller (1) I get them fired up when I'm done with them for the season, dump the tank, and just as they stall out I pull the choke.

Next time they are placed in service they get fresh fuel and good to go.

The only piece of equipment that I use rec gas in is my boat, and only the first and last tank each season. All summer long it gets a steady diet of E-10 and flawless. Last outing of the year I run it down pretty far and top off with 90 octane non ethanol and put it away for the Winter. It's fuel injected so I don't shut the fuel off to the engine. So far zero issues.

As much of a PITA as it might appear it's not much more than a small change to the shut-down procedure for most of it.

I'd also add that equipment that I use a LOT doesn't go thru any of that as I'm moving enough fresh fuel thru it to avoid any potential issues......