Does gasoline "spoil"?

I have a 2003 Mini Cooper S that has not been started or run for about 15 months. After recharging or replacing the (dead) battery, can I just restart the engine, or will the old gasoline in the tank have “spoiled” and harm the engine?

Try it. You will not harm the engine.

Most likely your car will start, although it might run a bit rough. Or maybe it will run smoothly. Whoopee. If you do experience starting problems, try using some Quik-Start spray or equivalent before you do anything drastic such as draining the tank and clearing the fuel lines.

Gasoline does “spoil”…theoretically. And it leaves varnishy residues in places where they should not be.

I’d be inclined to put some injector cleaner in the tank and start it up. When going away in future it would be god to put some gas stabilizer in the tank.

More importantly, check at slow speeds before you go anywhere and be sure the brakes are working smoothly and properly. You don’t want to try to stop in traffic and have the car shake your fillings out.

is drainas much gas out as you can. then replace gas filter. I would only put 5 gallons in incase there is a problem and need to drop the tank.but a 2003 should be clean inside. through some good cleaner in gas tank first then gas bounce car to mix it up. remember the old gas has been seating in fuels lines the smae time. if it runs check all rubber lines gas, brakes ,and water. rubber will go bad just seating around, check plug wire also and check plugs. if this an automatic I hope the trans clutchs are dryed out I would put trans in gear forward and reverse
for a few minutes to get everything wet in trans. change change motor oil and trans oil asap I don,t care it book tell you to wait for more miles . great little car I was one of first people to have a mini in the usa… Mine was a 1959. sorry I sold it . I only paid way back then $150.00 for it the first owner did know any thing about cars it needed a head gasket. I brought it home inside a uhaul trailer.

Gasoline does have a shelf life. 15 months is longer than it should be stored. With luck it was nice fresh gas to start with and now it should not be too bad. If it starts and runs OK it is OK. However I would not try to put it back in storage with that same gas.

If you know you are going to store a car over a few months, it is a good idea to add some gasoline stabilizer to slow the aging process.

You might err on the safe side and fill some gas cans and fill tank before starting car. If later it’s determined tank has to be drained then it would have had to have been anyway. '00 and up Jeep Cherokees that had sat on our lot a few months wouldn’t even run, mostly because it was, say, Fall and now they required the Winter gasoline blend. (Gasoline is blended differently season to season and region

to region.) I have to admit these Cherokees were way more “allergic” to old/wrong gas than other vehicles. No guarantees, but I have a feeling there won’t be a problem.

To find out if there’s a problem with the gas, remove the gas cap and take a sniff out of the fill tube. If it smells like gasoline the engine will probably start. If it smells more rancid, you’re going to have a hell of a time starting this engine.


Gasoline is made of mixed materials and none of them are friendly to the others. They are just pretending to be settled like an equilibrium state, so once the agreement has expired they go into a sectarian civil war, sounds familiar?

I’ve had a chance to sample some vintages (2-5 years old), the test vehicle looked okay other than emitted toxic fumes. Depending on the storage conditions/brand of gasoline though you’d better avoid them. Gas price should be cheaper than repairing any damage could happen to your engine.

I had some gasoline go bad in 5 months on one of my project cars here. The carb was rebuilt, fuel lines and tank drained and flushed out, and the fuel filter changed.
Added fresh gas and it ran great. Allowed it to sit for almost 5 months and finally got around to dinking with it some more and it would not even cough no matter how long I cranked on it.

Removed the air cleaner top and the house paint smell appeared so the gas had gone bad already in that short of a time.
Drained it all out and when a match was thrown into a small sample on the floor it would not even ignite at all.

Consider adding a can of SEA FOAM to the gas it is a great cleaner and gas stabolizer. then drive on.