Quote Originally Posted by OngBonga View Post
We don't dig petrol out of the ground, we dig oil out of the ground and refine it into petrol. There are stabilisers available which can be added to petrol to increase its shelf life, but you'll only add that if you intend to store it yourself. It's not mixed into the petrol at the pumps.

Diesel lasts longer, but from what I can tell, still only 12 months or so. Petrol keeps for 6 months. If you've got fuel sitting in an idle car for longer than that, it can cause problems. If it's half a tank or less, you can likely just top it up with fresh fuel and all will be well.

Point is though, petrol needs to be sold within a few months of it being refined.
petrol/diesel become thicker over time and clogs up fuels filters /injectors etc

https://www.briantsltd.co.uk/why-does-petrol-go-stale/