have any of you ever ran regular 87 octane gasoline on your E60, preferably in the I6? i'm just curious how it ran.

please, no "bmw recommends 93 and you should not run 87 octane" responses, i already get that and don't care to hear it again. i just want to know if you've done it and your findings.

 

i havent done so but its fine. i feel as if running a lower octane at a higher end gas station i.e. shell or cheveron is equal to running 91 at arco or valero

 

I have and found no noticeable results/behavior. I have also ran mid grade with no problems which I run a little more often. I have to say I couldn't tell you what is actually in there if comparing. Maybe there are some issues when it comes to really getting on it or driving it harder. My old M3 could not run anything but >97 otherwise, it rattled like crazy. I don't run reg. in my 535 LCI but did one time because that was all that was available.

 

although running a tank of Reg isn't going to do any damage to your motor i still wouldn't run it unless you have no other choice
and if you do have to run it i would stay off pressing the accelerater to hard.

Im not sure what the compression ratio is in the 525/530 I6's, but if BMW is recommending 91 octane its most likely a 10:1 ratio or high.
when you run a lower octane gas on a high compression engine you will get Ping, Luckily the ECU has little ears next to the cylinders called knock sensors that let the ECU know to pull back timing. When you lose Timing, You lose performance.
Once you fill up with 93 again the ecu will start adapting to high higher octane fuel and increase timing again.

To save $6 on a tank of gas by using Reg instead of Prem is not worth it

 

I did a 3k mile drive at high speed from Oregon to Utah in 2009 and tried regular for several tanks. No negative effects other than a loss of 'pep' (sluggish to get up and go) and a decrease in fuel economy.
My notes from the trip indicated a 16% decrease in the MPG I was getting (25mpg with premium and 21mpg on regular (87 or below)).

 

I have been driving BMWs for 10 yrs....mostly M52TU, M56 and M54 engines. I actually noticed better responses to throttle with 87. However, I now use 93 exclusively....why? Because if you look at the money you spend on 93 over a 5 yr period compared to what it will take in repairs to do a real carbon flush, fuel filter, spark plugs etc etc....you're better off with 93. The damage you cannot fix is inside the engine....and who knows what that is.

 

Is that a typo?
cheers
vern

 

i've run regular and could not tell the difference.

to complicate the issue even more, i have heard that bmw's are sensitive to ethanol, and that premium tends to be higher in ethanol content because ethanol raises the octane of gasoline. i don't really know if this is ture.. but i stick to mid grade as a result.

 

No not a typo...but i should clarify that it's noticeable at more times than others. It's an off/on thing. There's no real "truth" to it just what I've noticed.

 

Long term you are going to ruin the engine. Ping which is known as pre-ignition is a condition in which the fuel air mixture ignites before the piston has reached the top of its travel. Using lower octane fuels will cause this especially if the engine is a higher compression ratio which determines the need for a higher octane fuel. Eventually if the ping condition continues to be severe enough and over a long time period, it can actually cause damage to the tops of the pistons. so is it really worth it to save a few dollars now and have a major repair expense later? thats up to you folks. Ping is also described as ball bearings rattling in a can.