Does fuel have a best before date?

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Major Eazy

Major Eazy

Active Member
Posts
142
Location
Worcestershire
Before the lockdown started, I filled up my car for a long journey, I got almost a full tank. Then the lockdown started on 23rd March, so I cancelled the planned journey.

For past weeks, I only drove to the supermarket once a week, and I usually drive in the opposite direction and drive around the blocks. I'm not an expert, but I figure that would help keep the engine in good working order, if I try to add a few more minutes of driving time to my trip to the supermarket. I also figure it would help the battery too.

But I still got almost a full tank. Then it got me thinking. Just out of curiosity, does fuel (in my case, diesel) have some kind of shelf-life? Some kind of best before date?

Normally I tend to have a quarter tank full, it's enough for my needs, usually last me a couple of week, then I would just stop at the service station and add some more fuel. But that is the first time I've still got the same fuel in the tank for like 7 weeks.

Does fuel kind of get sticky or lose its powers, or something? Does it end up with something floating on the top, or have something settle down on the bottom? It's not like I can magically pick up my car and give it a good shake to stir the fuel. Drinks have shelf-life, I thought why not fuel?

I figure, if it will be fine, then great. But if not going to be fine, I figure why not drive around the edge of the town to pill on more miles to use up some fuel, so I can finally get to add fresh fuel. So it is something to worry about or not?
 
jamesmartin said:
if you were leaving it a few years it might be a worry but not a few months
Click to expand...

That's great then, thanks.

I was wondering if by the time the lockdown finally gets lifted, and I can travel, I thought I would have to drive something like 50 miles to use up stale fuel and flush it out with fresh fuel. Okay, so few months is fine, but not years, got it.

Once again, thanks.
 
Major Eazy said:
That's great then, thanks.

I was wondering if by the time the lockdown finally gets lifted, and I can travel, I thought I would have to drive something like 50 miles to use up stale fuel and flush it out with fresh fuel. Okay, so few months is fine, but not years, got it.

Once again, thanks.
Click to expand...
Isn't there a saying
"there's no fuel like an old fuel "
 
raywin said:
Isn't there a saying
"there's no fuel like an old fuel "
Click to expand...

Not heard of that saying. I was thinking more of the better safer than sorry proverb. In my 13 years of driving (10 with Ford Focus, and past 3 with Freelander), I've always drove almost every day or every few days, and always filled up every week or two, depending on how much fuel I used up and needed for other journeys, but this is the first time I've left my Freelander with a tankful of the same diesel fuel I filled up 7 weeks ago.

It's just great that @jamesmartin pointed out, it would be fine for a few months, but not for years.
 
jamesmartin said:
if you were leaving it a few years it might be a worry but not a few months
Click to expand...

No worry at all, till last year I’ve been starting up my classic car in the garage four times a year with 10 year old petrol in the tank and moving it onto the driveway and letting it fast idle and then reversing back int the garage.

What did happen was the garage smoke detector activated, but more importantly so did the garage carbon monoxide detection sound it’s alarm.
There no activation of any garage detector with my modern every day which is car parked alongside and filled with petrol once a month, so many proves the quality of petrol can deteriorate over time but the car still starts and engine runs without issues.

No issues with garage CO alarm detection now, as from last year the classic is on the road again and refilled with super unleaded as an MOT and tax isn’t required any more :)
 
I have owned sailboats with diesel engines for many years and have not read of diesel fuel itself going bad. It is a fairly stable hydrocarbon. What can happen with very long storage is that you get some accumulation of water in the tank and a type of algae will grow in this water and can clog your filters so most boaters use a fuel stabilizer to be safe. This is basically a herbicide for the algae and, I guess, some anti-oxidants. Petrol does not age as well as you have hydrocarbons more susceptible to oxidation. In addition the very light hydrocarbons like propane and butane which are necessary for starting in cold weather tend to leave the liquid. I think petrol that is a few months old would be OK but would hesitate if it was more than a year old and had no stabilizer as it might foul the plugs.
 
Modern petrol goes off due ethanol - and it also attacks various rubber derived seals and pipes...

Derv can be stored for donkeys years without issue - as post#9 - water condensate allows algae to grow, and this can make a right royal mess - but very rare in a vehicle - again, as said, boats and storage tanks more risk... Also, given your tank is full, this is less surface area for water to condense on, therefore even less risk :)
 
Disco1BFG said:
Modern petrol goes off due ethanol - and it also attacks various rubber derived seals and pipes...

Derv can be stored for donkeys years without issue - as post#9 - water condensate allows algae to grow, and this can make a right royal mess - but very rare in a vehicle - again, as said, boats and storage tanks more risk... Also, given your tank is full, this is less surface area for water to condense on, therefore even less risk :)
Click to expand...
I have seen algae in heating oil out here they use almost the same spec for heating oil and red diesel, normally grows if oil is left over the summer, it is a pain as it block the filter up and sometimes the pump, I have been told it is from the tankers that deliver the oil not being cleaned out, I think it is a water problem, but if bad the boiler will only run for a hour or so then will need filter cleaning
 
It’s the introduced bio content which messes up long term fuel storage, along with vehicles that use adblue tend to have a finer filtration system
 
I tend to keep my Disco 2 topped up fully.
When down to half tank I then fill it right up.
Mileage is(before lockdown) about 5-6000 per year
Also never buy supermarket fuel, except Tesco, which is ESSO.
And I add 2SO every time I fill up. This helps lubrication of pump and injectors.
142k on clock and not even a puff of smoke when starting.
 
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