It probably goes without saying here...
...but as a reminder (the kind I sometimes need myself)
Keep a reserve of gasoline/diesel on hand that has been dosed with Sta-Bil (or the like)
I refuel my tractor (JD/diesel), chainsaws, camping generator, etc with those stores to keep a slow but steady rotation going.
In a prolonged disruption of replacement supply, they would then be gold. And rationed out for only the most critical uses, even months past untreated fuel.