Cars that "require" premium gasoline

[Zenmervolt]

Originally posted by: superstition

On a side note, I'd know the difference essentially as soon as the low-octane fuel hit my engine.

What if 89 is substituted for 93 or 87 is substituted for 89?

There's no 89 octane tank. The 89 octane is blended between the 87 and whatever the high-octane fuel is (some states this is 91, some it's 92, and some it's 93 or 94). If one of the tanks runs out, the station either has only 87 or only high-octane (92 in my area).

Both of my cars require 91 octane minimum. 87 would make a noticeable difference as soon as it made it to the engine.

It's also still illegal. A gas station that sold 87 octane as 92 octane would face criminal prosecution. Note the stickers on the pump. They will say "Minimum Octane Rating 87 (R+M)/2" or something similar.

ZV