system
Given the following post, respond as if you're commenting on Reddit:
human
What are the differences between the types of gasoline at gas stations and how does it effect your car engine if you put one grade in over another?
gpt
The efficiency of an engine depends on the *compression ratio*, which is the internal volume of the cylinder with the piston at the bottom divided by the volume with the piston at the top. The higher the compression ratio, the more energy goes into turning the crankshaft and the less goes out the tailpipe.

So you want the compression ratio to be high. Unfortunately, if it gets *too* high, the fuel-air mixture will detonate instead of burning progressively. This means the piston gets a hammer blow instead of a push, and it can wreck the engine.

The maximum compression ratio your engine can tolerate depends on the chemical makeup of the fuel; some fuels let you go higher than others, and the *octane rating* is a measure of this ability.

Your engine is designed to use fuel of at least a certain octane rating. If you use a lower-rated fuel, you're risking engine damage in a hard acceleration. If you use a higher rating, it won't *hurt*, but you're throwing money away because it won't *help* either.