I just aint sure about my a4... i know it needs premium gas but my car's old owner always fill it up with regular gas... what the heck... what should i do? just stick with reg or prompt it to premium? more power?

Thanks

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ZaM

If you put things that are lower then the minimum requirement, the car will not like you.

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2005 Lighting Yellow Lancer EVO 8
2000 Audi S4 Imola Yellow
1997 Porsche 911 C4S, Black

use premium. you get higher mpg with higher octane levels anyway

and yes, you get more power. Higher octane number=more energy in the fuel, as it lets the engine run at a higher compression rate, delivering more power.

Higher octane fuel does not have more energy. It does allow for
more boost and ignition timing advance.

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2001 A4 1.8T Q Casablanca White, Tip, ESP, Xenon and Premium

So true, it actually has slightly less "energy". What it is, is more thermally stable. So it doesn't pre-ignite & cause a ping. This allows for more boost (F/I cars) & timing advance. On non turbo cars, you can run higher compression & get more power.

The static compression ratio can never change. What I think you meant is you can run higher boost?

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2005 Lighting Yellow Lancer EVO 8
2000 Audi S4 Imola Yellow
1997 Porsche 911 C4S, Black

LOL! Classic

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00 A4 1.8T

01 S4 for sale, PM for details. (sale pending!)

But a car can be designed (or maybe modded) with a higher compression ratio if the maker knows that they're going to require higher octane fuel.

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2002 A4 1.8T Quattro 5 Speed
1969 Camaro 307SBC/TH350

my car says that it need premium but the minumum octane rating is 87, i assumed this is for europe, but for the short time i took 87 octane i notcied several thing, im pretty sure the car realized it was getting cheap gas and therfore retarded the timing, i had slightly less power, i would average about 250mile on a full tank with some spirited driving in a city enviornment. once i realized what i was doing, i seafoamed everything and started using premium ( always shell BTW) with that i feel more power espacially in the low RPMs and it pull alot better throughout the powerband, i know get about 300 miloe per tank with some spirited driving. all in all just use premium the 20 or cents you pay extra is really worth it.

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An audi without quattro is just a VW

the octane rating determines the burn rate (of the fuel)...

depending how your engine was designed it may need a specific octane rating for the fuel used.

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