Firstfives.org

Box stock 528i. The corner gas station offers 87, 89, 92 octane,... black type on yellow squares.

That's it, and I am too lazy, uneducated to have played the translation game, RON, EPA, ethanol mix, blah, blah toot.

I have run 87 for years, no audio knocking, noticeable plug effects. Have I been lucky, stupid, depriving myself of zoomy fun ?

8.2:1 compression. Unless you're cranking in a ton of extra advance, basic 87 regular is all you should need. And aside from should, if it's not pinging or detonating you don't need any more.