How bad is old fuel?

[mattjeanes]

I've heard a lot of mention on this forum and elsewhere on the perils of old fuel. I have left fuel in my motor all winter for a couple of years now and I have also used fuel that has sat in the tank all winter. Having done so I was expecting to find gum and varnish in the carb when I dismantled it, but to my surprise everything looked absolutely great. Is old fuel really the big issue that everyone says it is? If I use the tank of fuel that's been sitting in the shed since last summer should I expect problems other than mucking up the carb? (which doesn't seem to happen)<br />Thanks in anticipation of much wisdom and possibly some disagreements!

 

[Mark42]

Re: How bad is old fuel?

I think the problem with old fuel is not so much the fuel but the fact that many times it slowly evaporates from the carbs, being replaced continually until all that is left is the brown varnish build up.<br /><br />I have not had problems leaving fuel in motors all season as long as the fuel line is shut off. Sure the gas in the carb will evaporate, but will not leave enough of a film to be a problem.<br /><br />The old fuel is missing some lighter elements that make for easier starting and help clean the system. But if mixed with fresh fuel, it is fine to use (according to the major oil companies).

 

[Barnacle_Bill]

Re: How bad is old fuel?

I have used fuel up to a year old with no problems and have seen some a year old that would not fire. I think a lot of it has to do with the type of container its stored in and where its stored. A metal container or tank will have more problems with condensation. If there is any doubt, do like Mark42 said and mix it with fresh gas. If it is several years old, I wouldn't even do that, I'd get rid of it. Why take the chance.

 

[reeldutch]

Re: How bad is old fuel?

i always dump old gas in my old jeep.<br />hate to waist gas.<br /><br />reeldutch

 

[PDS]

Re: How bad is old fuel?

I've used old gas(2-3 year old) in chain saws, leaf blower, and weed eaters(all 2 strokes)some very inefficient engines and they worked fine, but using 1 year old gas in an outboard gave me problems(It ran best at half choke) I hate to waste gas, so I use my old stuff in an old rider lawn mower. My 2 cents. PDS

 

[Vic.S]

Re: How bad is old fuel?

I have regularly used old fuel BUT I always transfer it from the plasic ob tank to metal cans for storage and I only keep cans that are full.<br /><br />The object is to minimise exposure to air (Polyethylene is permeable to some extent) and also to light.<br /><br />I also filter all stored fuel before use. I have a fine fuel filter in a syphon tube to achieve this. The only time I had problems was when I didn't filter the fuel.<br /><br />The oil itself can deteriorate, at least I had the last bit in a bottle (several years old) go all "lumpy" on one occasion

 

[WillyBWright]

Re: How bad is old fuel?

A few years back a guy brought in an old motor and a tank of gas. It was his father's or something and hadn't been run in over ten years. I expected the tank to be junk along with the gas. I opened it up and it smelled perfectly fresh, like the day it was pumped. It was completely full which left little air to oxidize the gas. It was also kept in the basement on a wooden plank. The cool and constant temperature and insulation from the corrosives found in concrete also helped.<br /><br />Stabil leaves a thin layer on top of the gas in a tank of gas to block oxidization. It's quite effective for months at a time. Years would be pushing it.

 

[BoatBuoy]

Re: How bad is old fuel?

Vic,<br /> It wasn't Amsoil that went lumpy, was it?

 

[rodbolt]

Re: How bad is old fuel?

I like oldfuel. leaves a nice shuny black laquer on the piston skirts. i make decent money rebuilding motors run on sour fuel. espescially pre-mix sour fuel. if you have 20 gallons of sour fuel and add another 20 gallons of fresh fuel you now have 40 gallons of trash. back when i would work on blow boats it was a constant problem. 20 gallon below deck tank and a 6hp kicker that never ran. some people use old gas and get lucky. others get a set of pistons and a tank flush. roll the dice and pray for 7 or 11.

 

[Vic.S]

Re: How bad is old fuel?

BoatBuoy, <br />No it was not Amsoil, I've not heard of that in the UK. I was so long ago that I really can't remember what it was though.

 

[tabbott]

Re: How bad is old fuel?

Old gas might make a good parts cleaner. You won't find it in my o/b tank though. Look at all of the carb related posts on this site alone. Factor in the cost of repair or time spent eliminating the myriad of problems proven to be associated with fouled fuel. I don't believe there would be an adequate reason that could be provided for using the stuff in anything much less a boat motor. I hate wasting anything myself but, I do take out the trash daily! Throw it out!

 

[DHPMARINE]

Re: How bad is old fuel?

Always thought if it was old enough to have to ask about it .....<br /><br />DHP