hello, i just bought a 1999 bmw 323i and i would like to know which gas it's the best for it? a mechanic told me that i should put supreme(93) but i would like to know if you guys would do the same?
Read your owner's manual. If it calls for premium, then use it. It is more important that you use a proper "top tier" fuel. This means, that it has met the qualifications of various car manufacturers for detergent, volatility, burn speed, and ash creation. BMW used to test each available fuel. Several years ago, only Mobil, Marathon, Chevron, and Exxon passed their tests. Now, Shell is also passing. READ YOUR OWNER"S MANUAL!!! If regular gas runs ok, use it. If your manual says that using regular gas will alter the timing or fuel efficiency, then UPGRADE. If the engine "pings" under acceleration, UPGRADE. Good Luck!!