Old Petrol

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I've got 3 large (25 litre) outboard tanks that each have about 10 litres of unleaded petrol in (no oil mixed in) that have sat unused for 3 1/2 years.

I am thinking that if I just top up with new petrol (so old 10 + new 15 litres) then all will be fine.

Thoughts?

(or should I have mixed it with diesel and used it to start the local guy fawkes night fire? BOOM)

 

[William_H]

Old petrol

If you have a petrol car (or lawnmower etc) then i would use it very diluted in the car. If you use some of it up this way then yes I feel sure the remainder wwill be OK diluted by new petrol. olewill

 

[rob2]

Yes, about a third by volume of stale petrol will go unnoticed, especially if the new stuff is the higher octane stuff! Otherwise, you might find the engine a little rough running and not so eager to start, not much fum if you have a hand start!

Rob.

 

[Twister_Ken]

Don't put it in a modern car if it's not unleaded as it will screw up the catalyser.

 

[Lakesailor]

each have about 10 litres of unleaded petrol in (no oil mixed in)

I've never had a problem with "old" fuel. If you are dubious top one tank with fresh and see how it goes.

 

[Ex-SolentBoy]

I ran a lawnmower this week on 2 year old fuel. It got rougher and rougher, poured out smoke for a while and then stopped.

Replaced with new fuel and ran perfectly.

Old fuel still lit the bonfire though.

 

[VicS]

Petrol will keep for a while if stored in full, tightly capped, metal cans... To minimise exposure to air and to prevent loss of lighter fractions.

3½ years is bit too long! and 10 litres rattling around in a 25 litre tank is not a good way to store it.
However as suggested mixed with at least an equal quantity of fresh petrol may be OK. Worth trying in the lawn mower at least

I always filter stored petrol before using it ( although it's usually 2 stroke mix that I have stored)

 

[Matata]

Slightly off track....I've just drained 40 litres of unleaded mixed 50:1 with 2 stroke oil and been a skin flint want to burn it up in my ford focus. How many litres of pre mix per 45 litre tank do you think I could get away with before things go a bit pear shaped??? Now there's a hard one!!!!!! Nik

 

[CreakyDecks]

Slightly off track....I've just drained 40 litres of unleaded mixed 50:1 with 2 stroke oil and been a skin flint want to burn it up in my ford focus. How many litres of pre mix per 45 litre tank do you think I could get away with before things go a bit pear shaped??? Now there's a hard one!!!!!! Nik

When is your MOT? If it is in the near future I wouldn't start messing about with anything likely to affect the cat. If it's only just been MOT'd then you haven't much to lose, a new cat for a Focus is only about £70 and the petrol is worth that! I'd try about ten litres per full tank. My gut feeling is that over a year the very high temperatures of the cat will burn off any crud the oil leaves (but I have absolutely no idea whether that is true or not!)
At the end of the day you only have 0.8 litres of oil in there. My old banger gets through a lot more than that in a year and its emissions are always near zero!

 

[pagoda]

I've got 3 large (25 litre) outboard tanks that each have about 10 litres of unleaded petrol in (no oil mixed in) that have sat unused for 3 1/2 years.

I am thinking that if I just top up with new petrol (so old 10 + new 15 litres) then all will be fine.

Thoughts?

(or should I have mixed it with diesel and used it to start the local guy fawkes night fire? BOOM)

I would suggest adding no more than 5l per tankful. Old petrol tends to be less combustible than fresh stuff.
That said, I use any old stuff (including old 2 stroke mix) for starting bonfires for garden rubbish (very carefully- but it does work)

 

[Skylark]

I left my motorcycle unused for about 3 seasons with half a tank of unleaded fuel. The bike was stored in a (relatively) warm garage. When I wanted to put it back on the road this year I had all manner of problems in trying to remove a thick layer of wax / tar coating from the inside of the tank. Almost nothing would shift it. Finally, a strong, hot mixture of caustic soda did the trick.

I would not use long-time-stored, modern fuels in an ic engine.

I'm still pondering my car. It has had half a tank of 4-star leaded for 21 years. Come the day when I put this back on the road, I wonder about the condition of the fuel.