So here's the big question - what fuel grade do you use in your E60? This pertains to the DIY Section because I am curious to see if members add fuel additives when they use lower octane fuels...

I am in the South in the US and had a lot of hard starts using 91+ Octane. Really - the engine would idle rough before it "caught on." I spoke to my SA and he reccomended switching to an 87 grade fuel and sure enough - no more pinging or hard starts/rough idles. I use STP additives every five thousand miles to make sure I do not clog my injectors and am curoious if anyone out there has a similar problem/situation.

BTW - the 2007 X5 manual [our new car], clearly states using fuel grade <91 AKI does not void warranty.

 

91 is the highest octane we have here in cali and i think i could speak for most that 91 is what we go with, aside from racing gas being available. some of us have mixed 91 octane and 100 octane, giving us about 95 octane. ive even heard from some people putting straight up 100 octane in their e60s. as for additivies, i think it was mikebuzzsaw that mentioned something about using valvoline fuel injector cleaner additive once in a while and has reported back a little slight increase in fuel mileage.

 

Thanks for the reply. I was a firm believer in higher octane gas till I listened to my SA and tried to switch down to 87 [this is what the dealership uses for all it's loaner cars, incl 6/7 loaners btw]. I will now only use 87. The engine sounds better, my fuel economy is better and I don't have the rough idling as I used to. I have not tried additives - some concern about it as the manual says not to use fuel additives....

BTW - anyone have a nice DIY to change out your spark plugs?

 

I read something very intriguing this week - adding a small amount of pure acetone to your fuel will increase your mileage. Odd.

Maybe I'll try it out on my leased car before I turn it in.

I find it unusual that 87 octane runs better. Maybe you were getting bad 91 octane fuel?

Higher octane fuels are generally required for higher compression engines (which we have). The reason for this is that the flashpoint of the fuel is higher, which helps prevent detonation, pinging, etc. I would be cautious of running 87 in my car for very long.

 

I use 93 octane here in Texas (Premium Unleaded).

 

you really buy that? higher octance better? come on man, all gas run the same. 87,89,91,93 and all that. fill it up with any of those, your car still runs well. i use 87 in all of my bmw, 530i e60, x5 e53, 330i e46(sold) they all run the same. but here the the points, if you run DIRTY DIRTY gas from cheap gas stations and you dont clean your injectors, NOW that will hurt your engine. its pschylogical. even the SA told me, fill it up whatever you like. you think if there is something wrong they would take a sample of your gas and blame it on you for not using the recommended one? they dont. its totally up to your wallet. here, 93 is $3.10 and 87 is $2.60. thats 50 cents difference. multiply that by 40 gallons a week (~23 X5, ~17 530i) that i save $20/week, $1040/year if including long trips. thats about $1500/year.

 

In simplistic terms, higher octane gas is less volatile. In other words, it is more difficult to ignite. That is probably why you see a difference at idle, as the 87 octane gas is easier to burn.

However, this is a liability at other times, as the fuel will prematurely burn before being ignited by the spark plug. This is called engine knock.
Your car has sensors to detect knock, and is able to adjust the ignition timing to compensate. However, this results in a reduction of power and, as a result, a loss of efficiency.

As for which station you buy your gas from, in most cases, all stations within a region get their fuel from the same refinery.

 

Well, now we got ourselves a discussion. A few thoughts from my end:

1. Agreed -- all gas stations ultimately get gas from the refinery. But for the end user like you and I, how that gas is transported, stored and maintained is key. The "cheap" gas stations tend to have more residue in their tanks, poorly maintained lines, etc and don't ahve the stringent quality to check fuel density like other gas stations have. Plus..there is always the unsaid truth about mixing that goes on to help save on cost This H20 is lethal to your engine.

2. The higher combustion engines such as the N62 can compensate for engine knocking but yes, at the cost of power. Personally, I have not noticed any difference in the performance of my vehicle. When my rough starts and hard idles were occuring, the car went to the SA twice and no problem was found. It was my SA who reccomended I switch to a lower grade fuel.

3. I always buy Shell brand gas. Call me crazy but it was what my delivery specialist told me was reccomended when I picked up my car in Munich and yes, I do not lease but own this puppy.

4. Here's something I borrowed from another forum which will help further add fuel [sorry, couldn't resist that one], to the fire:

BMW uses the term "Premium Unleaded Gasoline" with the knowledge that state laws
vary with regard to the octane that can be advertised as "premium". 89 probably
represents the lowest end of the range of fuel commonly advertised as premium in
the U.S., so any fuel labeled premium will meet the minimum specification. To
answer the original question, no, 89 octane won't hurt his car, and yes, he's
wasting money buying 92. The only time higher octane is of any benefit is if the
car pings on the recommended grade, the timing is advanced, compression is higher
than stock, or the car has forced induction. Pinging occurs when the spark
occurs too early in the cycle. If the fuel/air charge is not compressed enough
(i.e. harder to light) the charge explodes rather than burning at a controlled
rate. The two means of eliminating this condition are to a) use higher octane
fuel which is more resistant to ignition and burns slower and cooler (roughly 1
degree per point of octane) or b) retarding the ignition timing. This is exactly
what happens when the knock sensor detects pinging. In response, the computer
pulls out timing to prevent the pinging.
92 is overkill for a BMW engine, i.e. more than is needed. It won't hurt it, but
it doesn't do any good either. If it makes you feel better to put premium in
your car, knock yourself out (yes, pun intended!)
For a good (and brief) explanation of how octane is measured, what AKI and RON
mean, and what it means to your engine, check this link:
http://www.exxon.com/exxon_productdata/lub...ane_number.html

Will wait to hear more comments -- and hey, where are all the STP/Fuel additive users???

 

Well 93 aki premium here is only 2.95. I maybe wasting money buying a more expensive gas but then I maybe wasting more money too in buying an E60 BMW instead of a Camry or a plain Toyota Corolla hehehe.


"you really buy that? higher octance better? come on man, all gas run the same. 87,89,91,93 and all that. fill it up with any of those, your car still runs well. i use 87 in all of my bmw, 530i e60, x5 e53, 330i e46(sold) they all run the same. but here the the points, if you run DIRTY DIRTY gas from cheap gas stations and you dont clean your injectors, NOW that will hurt your engine. its pschylogical. even the SA told me, fill it up whatever you like. you think if there is something wrong they would take a sample of your gas and blame it on you for not using the recommended one? they dont. its totally up to your wallet. here, 93 is $3.10 and 87 is $2.60. thats 50 cents difference. multiply that by 40 gallons a week (~23 X5, ~17 530i) that i save $20/week, $1040/year if including long trips. thats about $1500/year."

You save thousands more if you trade in all your cars to a cheaper Toyota or Honda. Just kidding.

 

yeah, you are right, most of us here waste our money on our e60 instead of camry and corolla. true that. fully loaded camry is ~$28K and fully loaded e60 double that. i heard over other boards about how fun to drive bmw. i think only "rich" (i know i am not) peeps want to have this kind of fun. so i guess saving a little on gas dont count here. i think its funny since i now drive both x5 (long-disctance-work) and 530i (in-city-work) and both of them are the products of the 4runner and camry trade-ins.