system
Given the following post, respond as if you're commenting on Reddit:
human
Why are their different levels of octane for gasoline (regular, premium, etc) and how does that effect my car (and why do some cars need regular while others need premium)?
gpt
To put this into something a five year old might understand...

Imagine we gave you three fully-blown balloons. We wrote 87 on one, 89 on another, and 92 on the last one. That number indicates how hard you can squeeze the balloon before it pops. You can squeeze the 87 balloon a little before it pops, the 89 balloon can be squeezed a bit more, and the 92 can be squeezed even harder. The harder you can squeeze that balloon, the bigger the pop.

Now to bring that back up to speed (ha-ha! car pun)...

The ratings you see on pumps (87%, 89%, 92%) correspond to the ratio of octane to heptane. Those chemicals aren't necessarily important, but it is important to know that the higher that percentage, the more the gas can be squeezed before it ignites and goes pop. Just like with the balloons, the more compression, the bigger the pop and the more power you get from it.

HOWEVER, your engine has to be designed to take advantage of higher octanes or else pouring 92% in an engine designed for 87% is just wasteful. On the other end, pouring 87% in an engine designed for 92% can be damaging to the engine.