What octane gas do you use?

[weiln12]

Originally Posted by kvc

I beg to differ. In my experience, I have far better fuel economy using a higher octane fuel, than 'regular'. Moreover, my engine seems to run smoother and is slightly more responsive.
As many others have said, the modest difference in cost to fill up your tank is akin to buying 'OEM' filters as opposed to 'generic' when servicing your car IMHO. I like to think I'm doing the best I can for my pride and joy, and she will perform accordingly, by providing reliability and pleasure.

This has been my experience as well. Heck, even in my FJ that "recommended" 91 but ran on 87....I ran it on 91 because the performance and gas mileage more than made up for it.

[Joshdub]

Originally Posted by StephenVA

Sorry for the Hi-Test Geezer term. Pumped gas in high school when 103/104 octane was leaded gas at $.36 @gal and when it went to $.50 a gal I thought that was high.

Back in the "Gas War" days I saw $.19 for 103 Octane

When I started driving gas was ~$4.00 a gallon for 91/92. Anything less feels like I am driving for free.

[kvc]

Originally Posted by trader4

I think your emotional attachment may explain a lot. BTW, I use
Fram, Mann, whatever name brand filters are available and change
the oil at 10K. 175K and all is well.

I wasn't implying you used generic parts when servicing your car. I was using this as an analogy. That said, it's entirely your choice what type of fuel you fill up with. You may even choose to use an ethanol blend, as it is less expensive and may provide you with satisfaction too. I was simply posting a reply and providing my opinion for the collective knowledge base.
As is clear to see, from Q's post, the recommendation from the manufacturer is to use a 'better' quality fuel.
Yes - I think it would be fair to say I have an 'emotional attachment' to all my vehicles, as I've worked hard to pay for them and unlike some other people out there, I treat them with the respect they deserve, as opposed to simply considering them as a mode of transport. If the latter were true, then I somehow doubt I would have bought a BMW (and other quality vehicles)... but since I have, I will continue to follow the recommended quality fuel, oil and filters in an effort to achieve a relatively trouble-free period of ownership and have peace of mind.

[brian1950]

In Australia 91 is the lowest octane rating, then 95. I use 98 octane in my 2004 X5 4.4i. Runs well.

[edogg]

Originally Posted by trader4

Here in the states you'd have a hard time finding gas that doesn't
have 10% ethanol in it. I don't know where I'd find gas in the
northeast that doesn't have it, even if I wanted it. It's not at
the typical gas stations, that's for sure. And it has nothing to do
with lower price, if anything it's increasing the cost of gasoline.
I guess now E10 is supposed to be bad for the BMW too and
I should feel bad for mistreating it when putting it in. On the other
hand, 175K miles and the engine is solid, performs perfectly fine
for me with regular E10 and no observable difference in MPG compared
to premium either. Your car, your money, your feelings, your choice.

E10 is bad for any engine. There are well-documented issues with its lower power, increased corrosion, breakdown of rubber, and water retention. It's unfortunate that we don't have much if a choice other than hunting down ethanol free gas (which you can find by visiting Ethanol-free gas stations in the U.S. and Canada).

[electricalserv x5]

Originally Posted by kvc

Octane ratings are a bit different over here, to what you guys use in the US. Our 'regular' fuel is 91 octane, 'premium' is 95 and 'ultimate' is 98. Fuel cover on my vehicle says to use anything from 89 to 100. I choose to use 98 (the best fuel available). The advantages are: more power, cleaner burning (just look at the plugs) and better economy. You may pay a bit more at the fuel station, but go that bit further down the road and end up with a engine that loves you. Nothing shits me off more than being stuck behind an under-powered vehicle, climbing a hill under full throttle, leaving me in their wake of un-burnt cheap fuel emissions.

I heard that nice.........................

[JCL]

Originally Posted by brian1950

In Australia 91 is the lowest octane rating, then 95. I use 98 octane in my 2004 X5 4.4i. Runs well.

That is because you use the Research Octane Number (RON).

North America uses AKI, which is the average of RON and the Motor Octane Number.

Two different test protocols, at slightly different rpm (600 vs 900, IIRC, on a single cylinder test engine)

You can't convert between the two unless you know RON and MON, but RON to AKI is about 6 points. Your 98 is like 92 AKI.

[JCL]

Originally Posted by YETTI

Just wanted to what octane rating you all use and your opinion on it. I usually run 89 with the occasional tank of 93. And I drive a 2006 4.4i

On my 2003 X5, my best mileage ever was on 89. No retarding of timing, no performance degradation. 87 resulted in a slight decrease in performance; 91 was throwing money away. That was on my local fuel.

The reason you get so many different responses is because fuel varies widely across different geographies. I knew my local fuel quality. When I travelling I bought 91 because I didn't know the local fuel quality.

What it says on the pump isn't necessarily what you get.

When BMW states 91 they are allowing for that wide variance. Some percentage of customers will need the 91, others not. If you get any reduced performance or reduced mileage on 89, buy 91. If not, save your money and buy 89.

Worry more about ethanol. It matters.

[JCL]

Originally Posted by YETTI

Yea not worth the headache is it bad that to switch between octanes of fuel because next fill up is going to be premium and I have been using mid grade for the last 6 months

Most pumps these days are blending pumps. The station has 87 and 91, two tanks only. 89 is just a 50 50 blend of the two.

[crystalworks]

Once again Qsilver7 with the "Johnny-on-the-spot" end game from the manual or service literature or wherever you pull your images from.

It's been well documented that 87 yields fewer miles per tank on this particular brand of vehicle. Unless we are talking BMW's really old stuff that uses the original versions of Motronic EMS computers from back in the day like my e30's. With gas prices being the way they are... 91/93 is at most an ~$8 ($.40/gallon) difference per tank. Does that add up over time... yes, for sure. If you fill up once a week, that's a lot of miles, then you are at $384/yr. Is that substantial? Depends on your financial situation, outlook, and philosophy.

Trader, as with other topics you buck the trend (which is fine) but saying others are wasting money or the like is not really true. I'm glad you experience no ignition retard or knocking with 87 and manage the same fuel economy on the lower octane. That is not true for most BMW owners and should not be considered a typical result. In most cases the ECU will compensate for the lower octane and the car will run "okay" (depending on your definition of okay) but you will lower your fuel economy slightly. It's kind of like recommending someone eat hamburgers all the time because you've done it and all is well... so it must be okay for everyone.

Personally... I'll stick with premium.