petrol how long does it last

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pistolpete
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petrol how long does it last

Post by pistolpete »

SO I'm aware that petrol goes off I assume it becomes less combustible and goes a bit thicker.
SO how long does it last in the tank before you would drain it off a year , two years. what happens if you try and run old petrol, will it misfire back fire run lumpy as hell. Also how do you get rid of it, my local dump will not take it any thoughts please

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Re: petrol how long does it last

Post by Hawaiis0 »

I thought it was diesel that goes gummy.

Petrol has a recommended shelf life of 3-6 months dependent on ambient temperature. Doomsayers speak of catastrophic internal engine damage if not binned.

Can be re-vitalised by adding fresh fuel if not too bad.

However, I'm sure some people have had petrol in their tanks longer than 6 months.
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Re: petrol how long does it last

Post by Lotus-e-Clan »

Hawaiis0 wrote:
Mon Sep 05, 2022 20:10


However, I'm sure some people have had petrol in their tanks longer than 6 months.
That’s me, for sure. It's not so much the tank petrol but the evaporation in the carbs, and stasis within the fuel line that bothers me. But so far, filling up for a winter lay-off, I've had no probs.
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Re: petrol how long does it last

Post by Marten »

Hawaiis0 wrote:
Mon Sep 05, 2022 20:10
I thought it was diesel that goes gummy.

Petrol has a recommended shelf life of 3-6 months dependent on ambient temperature. Doomsayers speak of catastrophic internal engine damage if not binned.

Can be re-vitalised by adding fresh fuel if not too bad.

However, I'm sure some people have had petrol in their tanks longer than 6 months.
I wouldn't store a car or lawnmower with E10 for the winter.

Old petrol will loose the volatiles first, so it will be hard starting when cold. Might loose a bit on the octane rating as well

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Re: petrol how long does it last

Post by rbgosling »

Yeah, I'd agree with Marten. The most combustible components will evaporate off, so the petrol will not ignite as easily.

Any water in the system will have a chance to settle down to the lowest point, where it can try to cause some corrosion.

Where it has evaporated, it can leave a deposit on the surface, which won't make your carbs work any better.

As for disposing of it, either run it in something you don't care so much about (lawnmower, someone else's car), or mix with fresh fuel and use as normal.
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Re: petrol how long does it last

Post by pistolpete »

SO if the water settles at the lowest piont, not only does all the stuff that makes the bang louder evaporate it will such in water as well.
SO its the lawn mower then. Trouble is my lawn is dead :D

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Re: petrol how long does it last

Post by KevW »

I often read about modern petrol "going off" very quickly. My personal experience made me conclude that it appears to depend on which fuel you buy.

To cut a long story short I had an Excel SE parked on my drive from September 2013 until November 2014 with a half a tank of UK Tesco 99 RON petrol. During this time I ran the car once a fortnight and noticed no drop off in engine performance with the car starting on the button every time and reving cleanly, right to the last when the petrol was almost 16 months old.
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Re: petrol how long does it last

Post by Lotus-e-Clan »

KevW wrote:
Wed Sep 07, 2022 18:32
I often read about modern petrol "going off" very quickly. My personal experience made me conclude that it appears to depend on which fuel you buy.

To cut a long story short I had an Excel SE parked on my drive from September 2013 until November 2014 with a half a tank of UK Tesco 99 RON petrol. During this time I ran the car once a fortnight and noticed no drop off in engine performance with the car starting on the button every time and reving cleanly, right to the last when the petrol was almost 16 months old.
This is what I found too. Won't ever use E10 (and haven't so far) unless I find myself stranded with no alternative, and then it would be only a gallon in order to hunt for V power or the like, to fill up on.
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Re: petrol how long does it last

Post by fueltheburn »

Interesting topic and partly subjective as it depends on how hard you use your car to notice any performance drop.

There was an experiment done many moons ago on a drift forum where ethanol enriched fuels were tested versus those that did not contain ethanol.

This experiment was conducted when Tesco 99 contained 5% ethanol and Shell Vpower (99 octane) contained 0% ethanol.

The drivers who knew their machines intimately could tell any drop in performance or ill running on a day to day basis. The test was relevant as many of the cars would sit with fuel still in the tank from previous meetings.
Peak performance was noted to be identical between fuels on the first day of filling up.

The following week - no real performance difference noted except for some saying a perceptible but dismissable difference in tone when running at peak.

3 weeks later
V power was noted to have not suffered any change in performance, yet Tesco 99 was perceived to have dropped a touch in peak power.

After the initial testing was performed, some folk did a back to back test on their cars on dynos using aged fuel. Peak performance was noted to have dropped off by around 5-8 bhp. Bearing in mind these cars typically run high BHP so the loss would only equate to around 1-2% for aged fuel.

If storing a car for a long time, use super unleaded which is 5% ethanol.
Store the car with a Full tank of fuel. Ethanol is hygroscopic so leaving zero room for water to be absorbed is the best option. A full tank also reduces condensation forming on the sides of the tank meaning less chance of a tank rusting.

There are special blends of fuel you can order online and use for long term storage that will retain all of its octane rating for up to 5 years after being left in the car.

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