I was just wondering if you guys feel the difference between unleaded premium octane and plus? I usually go for the plus (89 octane) and it feels pretty much the same as the premium (93 octane). Which type do you guys use?

 

Read the owner's manual, it says use 91 octane AT LEAST

 

You better start using 91+ before the valves start taping. I was in your situation except that the owner's manual in my 740il said that it was OK to use 87 because it had a knock sensor in it (even though the gas cap said 89). Well everything was fine for a couple of months until I was in a parking garage going up hill with my windows down, that's when I heard this nasty valve tap. Luckily I switched back and no real damage was done since I was driving like a granny. But, it's your car and your money so the car will still run on 87 just that I recommend that you don't. Good luck

 

It says to use 91 so use 91.

 

i use 94 always :S... highest one..

 

Do you use 89 to seriously save like 1.00 per fill-up?

Just use the good stuff.

 

If you have to ask that question then you my friend can't afford the car let alone the gas Premium 91+ please

 

I've been making my own fuel with a 4:1 gas to xylene ratio with most of my fills to keep my Mugen ECU happy, however I rarely fill up all the way and fill to at most 75% most of the time. 92 oct is the highest here without going to the $8 race gas.

I would not suggest you use Plus or anything less than 91.

 

i actually noticed a difference with the different gas i used ive been calculating for my last three changes here is what i came up with

*cheap wawa gas station 91 oct 23.4 mpg somewhat normal driving
*shell gas cost like 4$ to fill with 93 oct and got 24.6 with ALOT of vtec from about 30 min of racing a GT.
*now i filled up with BP 93 oct and not much vtec at all so far i got about 130 miles on a half tank so far so i think im on track for about 27-28 mpg.

another good point is you can feel the difference from 91 oct and 93 i usually wouldnt believe that but i felt the difference, it almost felt like the throttle response was better. just my 2 cents and experience. i would def go with the 93 oct or better its worth the extra 4 dollars i mean come on its 4 bucks every week or so, well atleast for me

 

Won't the ECU change his timings to run on the 89? After a few knocks (bad), it should adapt and run, but with less power (bad), as far as I understand it anyway.