BMW Four Cylinder 28xdrive

[Fraser]

Originally Posted by JCL

I would expect the same red line.

That means it would rev 2000rpm beyond peak power whereas at 7000rpm the 'detuned' six is only 900rpm above peak power. I can't see it myself.

[AzNMpower32]

Cool, apparently it only needs regular (91 RON) fuel. So its less thirsty and no longer needs midgrade.

[JCL]

I think that is the same as the current turbo engines. The 35i has a minimum of 87 AKI noted in the manual. You won't necessarily get full power out of that fuel, and they are likely to word it differently in the BMW USA owner's manuals given the variability in fuels in North America.

[Fraser]

Originally Posted by AzNMpower32

Cool, apparently it only needs regular (91 RON) fuel. So its less thirsty and no longer needs midgrade.

I'm sure it will run on 91RON but no doubt it will deliver optimum performance and economy on 95RON or 98RON.

[AzNMpower32]

Originally Posted by Fraser

I'm sure it will run on 91RON but no doubt it will deliver optimum performance and economy on 95RON or 98RON.

BMW used to be more specific on these requirements. In the 2007 3er manual, it states that 98 be used for the advertised economy and power, with lower grades to 91 possible (the N54 engine requires 95 minimum).

In the new X3 and 5er manuals, it simply states quality of the fuel is more important, and that 91 is the minimum octane level.

Wonder if and why they're leaving things out of the owner's manual.

[Fraser]

Originally Posted by AzNMpower32

BMW used to be more specific on these requirements. In the 2007 3er manual, it states that 98 be used for the advertised economy and power, with lower grades to 91 possible (the N54 engine requires 95 minimum).

In the new X3 and 5er manuals, it simply states quality of the fuel is more important, and that 91 is the minimum octane level.

Wonder if and why they're leaving things out of the owner's manual.

I guess the newer engines have 'smarter' ECUs that are more adept at managing the different fuel grades.

[AzNMpower32]

Originally Posted by AlexK

What are you talking about - the current US manual for new X3 says "BMW recommends AKI 91 or 89", in addition to saying that "minimum AKI rating is 89" and "do not use E85 fuel", plus stuff like "Fuels containing up to and including 10 % ethanol or other oxygenates with up to 2.8 % oxygen
by weight, that is, 15 % MTBE or 3 % methanol plus an equivalent amount of co-solvent, will not void the applicable warranties with respect to
defects in materials or workmanship." That, to me, is a pretty specific information.

BMW prints that in the US manual because they know that fuels in the US vary widely in quality and tend to be poorer than those sold in the EU.

The German version of those manuals (which are the ones I go primarily by) states what I mentioned in the other post, and I believe the Australians and other non-US members can back me up.

[JCL]

My 2008 535i owner's manual (Canada) says minimum 87 AKI, and some other words about recommended AKI. They appear to be more relaxed about Canadian fuels. Your problem is that you get too much crap fuel in the US, so BMW has always recommended higher AKI as an insurance policy to allow for the fact that some of your 91 AKI isn't really 91 AKI despite being so labelled. They have been doing it for years, and have many owners in the US convinced that their BMW engines can only run on 91 AKI.

91 RON is pretty close to 87 AKI for many fuels.

I do agree with Fraser that the newer engines have better DME controls over knock.