2009 535i 91 Premium Fuel Only?
05-12-2009, 05:29 PM
#51
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My Ride: 2006 530i, sports package
retired: 1988 325ic, 1988 520i (euro), 1989 525i, 1990 525it.
The factory has to put that 91 octane requirement on the car, because the EPA fuel consumption was figured with that octane. Lower octane will give slightly worse fuel economy, and fatten wallets of oil kings, but that's all.
05-12-2009, 05:32 PM
#52
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My Ride: 2006 530i, sports package
retired: 1988 325ic, 1988 520i (euro), 1989 525i, 1990 525it.
It's 20 cents between normal and 91 octane.
So that's $3.00 per tank.
That's 3 items of the dollar menu at SmacDonalds!
So that's $3.00 per tank.
That's 3 items of the dollar menu at SmacDonalds!
05-12-2009, 05:34 PM
#53
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Originally Posted by vijfje' post='876744' date='May 12 2009, 09:32 PM
It's 20 cents between normal and 91 octane.
So that's $3.00 per tank.
That's 3 items of the dollar menu at SmacDonalds!
So that's $3.00 per tank.
That's 3 items of the dollar menu at SmacDonalds!
05-12-2009, 05:59 PM
#54
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You should use the octane that the ECU/engine combo was optimized for. The standard BMW programming optimizes for 91 octane (US*) since that's what the designers of the engine design for when it comes to compression ratio. You have a limited range of octane that the ECU can adjust to by advancing or retarding the timing but why bother in the first place. If you use a lower octane the ECU will retard the timing which will lower your power and if you go below the allowed tolerance you will get pining or worse detonation. Why risk it for a $3 per tank?
*91 US = 95 Europe, US uses ((RON+MON)/2) and Europe uses straght RON number.
*91 US = 95 Europe, US uses ((RON+MON)/2) and Europe uses straght RON number.
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