Off fuel

[oversize]

A post by someone else prompted me to ask this question...

It seems to be quite common that fuel goes off, as I've heard many people complaining about the smell.  I gather that fuel lasts about 3 months before this happens.  Many years ago during the fuel crisis, it was common to put fuel into 44 gallon drums and be stored for very long periods in the backyard.  Back then I'd never heard of fuel going off.

So could it be that fuel doesn't last as long as it once did??

[Tony66_au]

Yep

[gf]

is it because the octane level drops with evaporation/ or the components of the fuel start to seperate for some reason?

[KenM]

I too remember fuel stockpiling back in the good old days of strikes and so forth, can't remember it going off either but I can make a guess that it has to do with exposure to air. If you fill a container to the

brim and let it sit without air to react with I think it would last much longer than a half filled one. That's my theory anyway.

[oversize]

Could it be the lack of lead?  Or other additives that don't last and contaminate the main ingredients?  Obviously the fuel companies don't want it to last a long time, so you HAVE to buy more....

[Tony66_au]

Fuel used to be fairly simple distillate of Crude oil with colour and lead added as a lubricant.

Modern fuels vary in composition from country to country, refinery to refinery and company to company and the mixtures are all commercial in confidence.

98 and 100 Ron fuel will go off within 6 months of manufacture, 92 not so much.

Basically as mentioned above keep the container pretty much chockers, store in plastic not steel and keep it in a cool dark place.

Got these tips from a Petrochemical bloke who works for Shell.

[Tony66_au]

Avgas 100 The Green old school hi lead stuff (Not the Blue Avgas 100LL) im told will last in drums for a year in good conditions before its not recommended for Aviation and im told it has been recovered from fuel dumps after years and still run fine in combustion engines but its getting hard to come by as it contains over 1 gram per lt of lead (tetra ethyl lead).

Im now told that the tetra ethyl lead is actually a stabilising and octane enhancing agent and that Avgas still has lead because they cant make a suitable unleaded Avgas yet.

Soooo the lead plays a part in the stability!

[gf]

Thanks tony! always wondered on this one. Anyone know anything on fuel stabilizers? good/ bad?