Eh, your car will run a little shitty with the old gas, leaving an engine without running it for extended periods can cause somewhat faster corrosion depending

Eh, your car will run a little shitty with the old gas, leaving an engine without running it for extended periods can cause somewhat faster corrosion depending on your environment, and old gas can increase things like various gunk getting deposited around your engine. All in all, a mild shortening of the life of your engine and perhaps triggering some maintenance sooner than otherwise. Realistically, not much. The people saying “bad for you” aren’t wrong but they also fail to mention the effect size. It’s not particularly relevant unless you want to own the same car for a few hundred thousand miles and absolutely minimize maintenance. (Small aircraft for example, you want to care a lot about these things because they’re very expensive, when the engine fails you’ll be thousands of feet above the ground, and a well maintained plane can last decades. Your daily driver probably doesn’t have any of these issues) There are various preventative things you can do to minimize the effects anyway. It’s one of those internet things where yeah they’re not wrong exactly but they need to relax. Having too much beer and cheeseburgers last night long term probably wasn’t the best decision, but you know what I’ll probably be fine. Leaking gas in a car for a long time is like eating too much fast food. Ok yeah not the greatest but are you the type of person who cares enough to never eat McDonald’s? Make your decisions according to your disposition and don’t take people telling you you’re wrong too seriously.