I hear varying opinions on this one. I drive an 08 E91, now at just under 10k miles. I have always filled it with regular unleaded. We used to have an E90 that we sold at 60k miles, also always was filled with regular unleaded. The dealer has said in the past as have many others that octane rating will not damage the engine, it just may not perform as well. My question is over the long haul, will regular adversely affect the engine versus premium gas?
You really should be running 91 or higher octane in this car. The motor was designed for the higher octane. Now the motor is able to adjust to lower octane fuel, but it can only compensate so much. Lower octane fuel burns faster than higher octane and not as evenly. So you can have ignition before the cylinder if finishing the upward stroke, causing knock. This knock can cause damage over the long term. You engine tries to compensate by firing the cylinder later to prevent this. You should see better fuel millage and definitely more power if you start using 91 or higher octane. When you spend $30K plus on a car, why scrimp on 20 cents a gallon? Use the fuel this car was designed for.
thank you for the information. since i have been using regular, do you recommend any of the additives or cleaners for the engine/tank that bmw makes? i have never really believed in those types of products, but that doesnt mean ive been right.
In my area,I can get 93 and use Shell V-Power,. IMO,additives aren't needed. Today's name brand gas has enought detergents to keep the fuel system clean. Now if you get a bad tank a gas,a additive may help.
If you use quality gasoline like Shell, Texaco, & Chevron, you probably don't need an additive. I do use BMWs additive on occasion, maybe once every 10k miles or something like that. There use to be a top tier fuel website. But it seems to be down. www.toptiergas.com.
I may throw in the BMW additive every 10K miles. I hope it doesn't cause a damn fuel pump problem. I'm not comfortable about the fuel pump issue on the X35 models possibly leaving me,the wife or both of us stranded on the road somewhere.
Top tier all the way, or nothing. I add a bottle of Red Line SI1, or Chevron Techron every 7500 at the oil change. I've also tried the Lubro Moly Jectron, and Ventil Sauber that Bav Auto sells...good stuff. I use their 5W-30 oil.
