Correct fuel for 1992 525i M50 Engine

[Morgenster]

I use 98 octane (European denomination) or 100+ octane when on LPG.
So what's that in US octane ratings?

[Sam-Son]

the minimum for the M50 is 89. 91 with any kind of chip

[philbyil]

as I installed a JC chip some years back

I am having a debate with my son over the correct fuel to use for the car. Since the M50 engine has 10.0 to 1 compression ratio shouldn't premium gas be used as opposed to regular. Premium always runs better but he wants to pinch some pennies because of rising gas prices.

[94_e34_525i]

The m50 has knock sensors so it really doesnt matter what fuel you put in it....unless you have a chip (which changes the timing) so you need 91...but 87 89 91 93 all work in the m50 (stock chip) it all depends on what performance you want...