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johnbmw6
01-17-2011, 07:49 AM
OK before we jump, I just read my hand book and spoken to BMW customer services about the fuel grade.
I Have the 550i M Sport which is NOT an M3 engine however the book states Premium 95 octane minimum 91 octane.

Now here in the UK, all basic fuels are 95 octane so do I need to put super in it or not? super being 98/101 octane.:dunno:

DXK
01-17-2011, 07:55 AM
Here is U.S. most of us fill up with 93 which translates to your 98.

AzNMpower32
01-17-2011, 03:44 PM
Just use whatever the manual says: If the UK sells above the minimum, then that's great. 95 octane is sufficient. Boosting it to something like 101 won't be necessary for advertised power.

For US/Canada: 95 RON = approx 91 AKI

johnbmw6
01-17-2011, 03:47 PM
Just use whatever the manual says: If the UK sells above the minimum, then that's great. 95 octane is sufficient. Boosting it to something like 101 won't be necessary for advertised power.

For US/Canada: 95 RON = approx 91 AKI Yes this is what the BMW engineer said today, his words "use a Premium 95 octane fuel" such as shell, Esso, BP. that will be ok for the power.

Needsdecaf
01-17-2011, 06:18 PM
OK before we jump, I just read my hand book and spoken to BMW customer services about the fuel grade.
I Have the 550i M Sport which is NOT an M3 engine however the book states Premium 95 octane minimum 91 octane.

Now here in the UK, all basic fuels are 95 octane so do I need to put super in it or not? super being 98/101 octane.:dunno:

95 RON (91 R+M/2) is the highest available in many parts of the US, especially the west.

Titanflux
01-18-2011, 01:48 PM
OK before we jump, I just read my hand book and spoken to BMW customer services about the fuel grade.
I Have the 550i M Sport which is NOT an M3 engine however the book states Premium 95 octane minimum 91 octane.

Now here in the UK, all basic fuels are 95 octane so do I need to put super in it or not? super being 98/101 octane.:dunno:

In which case I think over 95 you are unlikely to see any difference because the engine will just behave accordingly as it measures the combustion levels.

It will just mean that the valve timing will alter below 95 accordingly down to 91 (you'll never find less than 95 anywhere anyway) to eliminate pinking or something like that. The power available would reduce slightly and economy would worsen.

3 litre and above petrol engines in my experience were recommended for RON 98 (e.g. Super unleaded) and therefore you supposedly got worse economy and performance with 95. Personally with the 3 litre petrols I've had I noticed no discernible difference and stopped forking out for super.

Needsdecaf
01-18-2011, 01:55 PM
In which case I think over 95 you are unlikely to see any difference because the engine will just behave accordingly as it measures the combustion levels.

It will just mean that the valve timing will alter below 95 accordingly down to 91 (you'll never find less than 95 anywhere anyway) to eliminate pinking or something like that. The power available would reduce slightly and economy would worsen.

3 litre and above petrol engines in my experience were recommended for RON 98 (e.g. Super unleaded) and therefore you supposedly got worse economy and performance with 95. Personally with the 3 litre petrols I've had I noticed no discernible difference and stopped forking out for super.

Be careful making broad statements like that. There really is no hard and fast rule other than: it depends. More often than not, putting fuel a grade above what is recommended won't gain you much difference in power and economy. Sometimes it can help, sometimes it can even hurt. Depends on the engine mapping and how aggressive it can go.

In my Volvo, apparently the Swedish Engineers thought it would be a good idea to calibrate the ECU to be able to take advantage of up to 100 Octane (R+M). So the ECU will continue to advance timing, change fuel mapping, and lean things out based on what it's sensing. The reality is that the intercooling system is so substandard that the ECU is constantly dumping fuel to cool things down when the going gets hot.

Most cars are not nearly that aggressive. Some recommend 91 and won't even give you a boost when running on 93. Some recommend 91 and run fine on 89 or even 87. Some recommend 87 but run like crap on it and do better on 89.

It really does depend. Best thing to do is to experiment with different fills and keep track of mileage. But even that is subject to variations in actual driving conditions so.....

Found one of my favorite old articles (can't believe it's almost 10 years old!!!)

http://www.caranddriver.com/features/01q4/regular_or_premium_-feature

Titanflux
01-18-2011, 02:04 PM
Be careful making broad statements like that. There really is no hard and fast rule other than: it depends. More often than not, putting fuel a grade above what is recommended won't gain you much difference in power and economy. Sometimes it can help, sometimes it can even hurt. Depends on the engine mapping and how aggressive it can go.

In my Volvo, apparently the Swedish Engineers thought it would be a good idea to calibrate the ECU to be able to take advantage of up to 100 Octane (R+M). So the ECU will continue to advance timing, change fuel mapping, and lean things out based on what it's sensing. The reality is that the intercooling system is so substandard that the ECU is constantly dumping fuel to cool things down when the going gets hot.

Most cars are not nearly that aggressive. Some recommend 91 and won't even give you a boost when running on 93. Some recommend 91 and run fine on 89 or even 87. Some recommend 87 but run like crap on it and do better on 89.

It really does depend. Best thing to do is to experiment with different fills and keep track of mileage. But even that is subject to variations in actual driving conditions so.....

Found one of my favorite old articles (can't believe it's almost 10 years old!!!)

http://www.caranddriver.com/features/01q4/regular_or_premium_-feature

I am not sure which broad statement you think I should be careful about. I haven't suggested the OP should use a higher grade fuel than that stated in the manual. In fact I am suggesting that if that's the maximum recommended then he's unlikely to see much benefit, if any.

Needsdecaf
01-18-2011, 02:31 PM
I am not sure which broad statement you think I should be careful about. I haven't suggested the OP should use a higher grade fuel than that stated in the manual. In fact I am suggesting that if that's the maximum recommended then he's unlikely to see much benefit, if any.

Where you talk about 3 liter and above petrol engines.

Needsdecaf
01-18-2011, 02:34 PM
By the way, the owner's manual here in the US states that the minimum AKI is 89. Anyone in a 535 actually running 89?

johnbmw6
01-18-2011, 02:37 PM
By the way, the owner's manual here in the US states that the minimum AKI is 89. Anyone in a 535 actually running 89?That's the point I was making/asking, my owner's book says premium 95 or the minimum91, as 95 is the basic fuel here and the cheapest I am going to give it a chance and look at the economy verses the 98 Ron stuff.
If the 95 gives the same as 98, I will put the cheap stuff in.:thumbup:

Titanflux
01-18-2011, 03:17 PM
Where you talk about 3 liter and above petrol engines.

I used the word 'were' specifically because in the UK they WERE recommended for 98 RON, according to the owners manuals and BMW recommendations, for all 25i, 30i and 35i and 50i engines.

My PERSONAL experience with the 3 litre engines is stated.

The OPs manual currently recommends differently.