Does petrol get old?

[Crispin]

Folks,

I'm sorting out a generator for my mom in SA. She says she has a 25L jerry can in her garage with petrol in which is 3 years old. It's apparently remained sealed the whole time.
Any harm in using it? I don't want her to screw up the (annoyingly expensive) generator by saving a few ronds.

 

[Chris]

Yes it does. But probably not in a can like that. You may find being older that it's actually better fuel! If you leave it in the generator or chainsaw, lawnmower etc then yes some of the 'essences' do decay making things hard to start.

 

[Crispin]

...You may find being older that it's actually better fuel!

Like a fine wine


So even if it is old (for some reason) it just has less bang but won't cock anything up?

 

[Shayne]

When messing with bikes i would dump it as i would rather spend a few quid on petrol than have to remove the carburetor to clean jets .

 

[Chris]

Repeat. Does petrol deteriorate. Yes. But not typically in a can. No.

It might be better fuel not because it's matured, but because newer fuel is shite.

This isn't fuel in the gnerator tank. Now man up and stop fannying around like a Southerner.

 

[Crispin]

Thanks chaps.

Chris, you'd make a great shrink

 

[Tractionman]

As others on here, yes it does- but not to the detriment of the engine. Had a project car sat in the garage for for several years and only started intermittently, but increasingly difficult. After checking all usual suspects, a mate said "fresh petrol - old loses it`s octane". Yeah, right! After struggling on, in desperation filled a five gallon (yes gallons) jerrycan at garage, and dumped this in with the small amount already in there, after turning over and spluttering then roared into life and no more probs. Had the same effect with old lawn mower
John

 

[wobbly]

Modern petrol contains ethanol, which eats rubber components, which in turn changes the chemical composition of the fuel, which in turn screws up the fuel mixture.

Older Petrol in a can is ok if its been filled to the brim, as this leaves no room for condensation, but if its half a can I would chuck it as chances are it is now contaminated with condensate.

Or, go with Chris' suggestion, which i'm sure will be fine.

Let us know

 

[Towpack]

The volatile components in the fuel will evaporate if left in a ventilated tank or container leaving the less combustable stuff behind. I don'y lay up the bikes over winter any more but the road bike may go 2-3 months between runs so I always brim it and add some stabiliser which, curiously enough, smells very much like diesel or paraffin. I NEVER just start and run the engine now and again as some do. Had an FZR1000 in the early 90's which went unused for 3 months over winter with the tank around 1/4 full. Came to start it and it was very reluctant and smoked a lot when it did fire it ran like a pig. 2 gallons of new fuel in and within 5 mins it was perfect again. JMO

 

[t1pper]

Petrol does go off especially with today's modern fuels, I understand that after 90 days it will already be past its best. I am also a motorbiker too and I do not like to leave fuel in a bike over winter without an additive such as "Seafoam" as it tends to gum things up, for the cost of fresh fuel I would defo get new.