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Continuing Off Topic....
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Originally Posted by SANguru
I have to disagree with the 2nd part. As discussed many times before, over time you are doing damage to the engine. Engine will retard timing WHEN knock sensors say there IS detonation. Even when continuous monitoring, you still are getting the initial knock first for anything to happen. Over time, with detonation, you will have issues. Plain and simple.
The $$ that you save between premium vs mid or low grade is really little. ~10-20 cents a gallon. and say your fill up is 20 gallons. Well that's only $2-4 dollars a fill up. *52 weeks and that is only $104-208 dollars a week. If that's a problem, you shouldn't be buying a X5.
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I fully respect your opinion. Mine is just different. The knock sensors are measuring vibrations representative of pre-detonation, on every firing cycle, per cylinder. It is an active feedback. Any active control system is going to require a feedback loop. It all depends on the threshold setting, how severe the abnormal combusion is (or if it ever even reaches the knock point). It would be reasonable to detect pre-detonation prior to any severe knock condition). BMW does state in their literature that lower octane fuel will not damage the engine. They also rely on the sensors for other than low AKI fuel: they are there to protect the engine from fuel problems, exhaust problems, carbon build up, and other things that cause abnormal combustion. They have to have designed in a threshold level.
As to the $$ that you save, I agree. In my area, it is $0.12 per litre, 80 litres per week, about $10 per weekly fill. $500 per year, and that is for regular. I used 89, for half that saving. (Note: I don't use 89 on the twin turbo 3.0, it is illogical) For the E53, it was completely irrelevant in the economic big picture. For many, it is easier just to pay it and not think about it. For others, there is no option because they require 91 or similar from their local pumps or experience power and mileage loss, due to their local fuel quality.
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2007 X3 3.0si, 6 MT, Premium, White
Retired:
2008 535i, 6 MT, M Sport, Premium, Space Grey
2003 X5 3.0 Steptronic, Premium, Titanium Silver
2002 325xi 5 MT, Steel Grey
2004 Z4 3.0 Premium, Sport, SMG, Maldives Blue
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