Fuel Octane Recommendation for BMW X1/X2 M35i?
Posted by sushiloverbro@reddit | askcarguys | View on Reddit | 4 comments
I recently bought a 2025 X2 M35i and am a bit confused about which fuel octane to use. I’ve received conflicting information from my dealership — some have said 91 octane is fine, while others have suggested 93+ octane.
The manual first recommends 91 but then states that 93 octane is recommended for “M Performance model”. I’m not sure if the M35i is included in this category!
Can anyone with experience or knowledge about this clarify which octane is best for the M35i? Also, I’d appreciate any reasons or justifications for your answers, such as engine performance, fuel efficiency, or long-term reliability.
Thanks in advance!
gearhead5015@reddit
What does it say on your fuel tank cap or inside the fuel door?
If it says "premium recommended", then you can use 91.
If it says "premium required", then you need to use 93.
AshlandPone@reddit
I ran into this a few times with european cars, there's some discrepancy because everywhere outside NA measures octane in RON, But in NA we measure in AKI.
You'd see the inside of the fuel filler covwr have stickers for 91, 93 and 95... like where am i even getting 93 and 95.
Take a quick picture of your fuel recommendation in the manual. It will specify RON or AKI, and just show it to us. We can decipher what the manufacturer wants you to do, instead of us all arguing about fuel octane (which is a long drawn out and pointless conversation that only ends in agree to disagree)
Cranks_No_Start@reddit
Looks like there is one engine with 2 ratings. The 28I has 240hp and the M35i has 312 HP. Looks like if you have the M and you seem to then put in the good stuff.
SOTG_Duncan_Idaho@reddit
The manual says run 91, you can run 91. There is probably a small boost in performance and efficiency for running higher octane, but it's extremely unlikely to be enough to justify the cost.