[Corinne]

The official BMW information about which grade of fuel was used for establishing the performance figures states:

"Rated output: BMW recommends the use of super unleaded 95 RON fuel. Unleaded RON 91 fuel or higher with a maximum ethanol limit of 10 per cent (E10) is also permitted. The performance and fuel consumption rates listed are based on the use of RON 98 fuel".

I'm wondering how much difference in performance there will be if one uses, as recommended, 95 grade fuel.... and why on earth do they use one grade and then recommend another ?

[Makman]

Originally Posted by Corinne

The official BMW information about which grade of fuel was used for establishing the performance figures states:

"Rated output: BMW recommends the use of super unleaded 95 RON fuel. Unleaded RON 91 fuel or higher with a maximum ethanol limit of 10 per cent (E10) is also permitted. The performance and fuel consumption rates listed are based on the use of RON 98 fuel".

I'm wondering how much difference in performance there will be if one uses, as recommended, 95 grade fuel.... and why on earth do they use one grade and then recommend another ?

I agree. I think it makes some difference but not noticable. However, If you want noticable difference you should fuel V-power. That can increase hp with 15-25hp

[AlpsRider]

Originally Posted by Makman

I agree. I think it makes some difference but not noticable. However, If you want noticable difference you should fuel V-power. That can increase hp with 15-25hp

In the US we have lower octane fuel, I always use Shell V-Power.

[Makman]

Originally Posted by AlpsRider

In the US we have lower octane fuel, I always use Shell V-Power.

yeah you have like 89, 91 ans 93? I would never fuel my car with that. ..

[metrickid]

Originally Posted by Makman

yeah you have like 89, 91 ans 93? I would never fuel my car with that. ..

It is not RON like we use so you can't compare it like that.
It is AKI in the US so 98 RON is 93 AKI.

[Icsunonove]

Originally Posted by AlpsRider

In the US we have lower octane fuel, I always use Shell V-Power.

You don`t have lower octane rating, just different measurement method.
Among them, you have RON, MON, and AKI or (R+M)/2 which is average of the RON and MON.

So, 98 RON compares to 93 AKI and 95 RON compares to 91 AKI.

Most countries use RON, however, USA uses AKI or (R+M)/2.

So, If you live in USA, BMW recommends minimun use of 91 AKI which is 95 RON, or 89 AKI + up to 10% E10.
The figures of consumption and performance are based on 98 RON or 93 AKI.

[zenmaster]

Originally Posted by Makman

yeah you have like 89, 91 ans 93? I would never fuel my car with that. ..

Lol!

[Nahlem]

I prefer using Shell V-power due to Ron95 E10 have a tendency to cause more tare and wear on the engine and also for some reason i have a tendency to need to fuel up more often when using RON 95.

So i go with shell v-power, We had V-Power in Sweden without 5% E10 in it until a couple of years ago when for some reason they started mixing 5% E10 in the V-Power also so its classified as RON 98+ right now.

[Makman]

Originally Posted by metrickid

It is not RON like we use so you can't compare it like that.
It is AKI in the US so 98 RON is 93 AKI.

I learn something new everyday

[AlpsRider]

Originally Posted by Makman

yeah you have like 89, 91 ans 93? I would never fuel my car with that. ..

Yeah, it is pathetic, some states only have 91! I'm not sure if the rating system is the same but EU fuel us definitely higher octane. I had planned to use an octane booster and then I read that it can clog the injectors. What can we do?....

[hyperzulu]

Originally Posted by AlpsRider

Yeah, it is pathetic, some states only have 91! I'm not sure if the rating system is the same but EU fuel us definitely higher octane. I had planned to use an octane booster and then I read that it can clog the injectors. What can we do?....

Use Shell gasoline. There was a lady over at Bimmerfest who worked in a laboratory and did chemical analysis. She said of all the fuels available, Shell actually did burn cleaner.

Other than that, about the only thing you can do is actually use higher octane fuel, but I doubt it's really worth it unless you need it for tuning. There are a limited number of stations that sell 100 octane at the pump, but it's not cheap.

[chris719]

Originally Posted by AlpsRider

Yeah, it is pathetic, some states only have 91! I'm not sure if the rating system is the same but EU fuel us definitely higher octane. I had planned to use an octane booster and then I read that it can clog the injectors. What can we do?....

If you're not sure the rating is the same then how is EU fuel "definitely" higher?

Hint: Our top grades are the same. This was already answered twice in this thread.

[Nine Lives]

Also the better quality fuels such as Shell V Power have detergents and cleaning agents in them to protect the engine a little more,so it's a good move to use the best.
Here in the UK 99 Ron is readily available from one of our Supermarket outlets and has shown to be superior in a tuned N55 using a JB4 for example.

[AlpsRider]

Originally Posted by chris719

If you're not sure the rating is the same then how is EU fuel "definitely" higher?

Hint: Our top grades are the same. This was already answered twice in this thread.

Hint: You should read the thread too. I also said that some states have lower octane, 87/89/91 is the octane availabe at the pump in California with a population of 38 million people, CA is not the only state with reduced octane ratings. Yes I said the US but CA and the other states with lower ratings are part of the US, a big part. I meant to say that I don't know how that conversion works exactly but fuel octane is lower where I live CA/US. There is no need to wave your finger, all our grades are not the same as they have in Europe.

[gingiman]

Over here we've got mainly 95 RON (91 AKI)
There are a some gas stations that carry 98 RON, but not all do.
I would prefer using the 98 when available, but that would not always be the case. I would estimate that one out of every four tanks would have to be 95.

Would switching back and forth between 95 and 98 confuse the ECU and result in decreased performance? Would it be better to stick to 95 consistently?

anyone?

[ajvdh]

Originally Posted by gingiman

Over here we've got mainly 95 RON (91 AKI)
There are a some gas stations that carry 98 RON, but not all do.
I would prefer using the 98 when available, but that would not always be the case. I would estimate that one out of every four tanks would have to be 95.

Would switching back and forth between 95 and 98 confuse the ECU and result in decreased performance? Would it be better to stick to 95 consistently?

anyone?

In a word, "no". The ECU doesn't measure octane directly. It constantly listens for pre-ignition (knock), which can be caused by a number of factors including ambient temperature, barometric pressure, and load, as well as fuel octane. Give it 98 when you can find it.

Most stations around here only have 91. Our track has 100 no-lead, and I'll probably throw a few gallons of that in when I track the car.

[Bee Pee]

Originally Posted by Corinne

I'm wondering how much difference in performance there will be if one uses, as recommended, 95 grade fuel.... and why on earth do they use one grade and then recommend another ?

opting to use min grade recommended by BMW 95RON [Regular UL] in lieu of 98 [Super UL] - the latter being used for quoted engine output and performance figures - means giving up about 15-20bhp.

Out on the road, it will mean less oomph throughout the rev range as engines ECU adapts to lower grade fuel. There are dyno charts on the web showing how upper rev range performance is hindered as ECU retards ignition and boost to protect against knocking etc

[David1]

Originally Posted by Makman

I agree. I think it makes some difference but not noticable. However, If you want noticable difference you should fuel V-power. That can increase hp with 15-25hp

Don't tell me you believe that.

[weyland]

It has been observed and measured by a few TV programmes and magazines in the UK - it's a well known fact over here that using 98 or 99 RON performance fuel will give you increased throttle response and power (obviously results are car dependent)

[ried]

Higher octane will do precisely jack shit unless your car's timing is adjusted (it's "tuned") to take advantage of the more controlled detonation it offers.

[weyland]

Doesn't the ECU adjust the timing on most modern cars?

I've watched and read many articles were they have dyno'd a stock car, then run a few tank fuels of high octane fuel through it and put it back on the dyno and seen high readings.

When I have used it on my own cars the difference is apparent once the ECU has recalibrated for it.

[ajvdh]

Originally Posted by ried

Higher octane will do precisely jack shit unless your car's timing is adjusted (it's "tuned") to take advantage of the more controlled detonation it offers.

And the M2 is one of those cars, hence BMW recommending 98 (RON)/93 (AKI), and requiring a minimum of 95 (RON)/91 (AKI). You will lose power if you use the minimum grade, and, depending on other factors (altitude, temperature, relative humidity), you may fatten up the torque curve a small amount if you go higher than recommended.

I know when I go to the track, I'm gonna be splashing a few gallons of 100 (AKI) on top of the 91 which is the only choice at most stations around.