Thelman

89 octane. Will it just hurt performance or the engine as well?

myke050

Never put "regular" (below about 90) into a car with a dedicated turbo-charger and complex machinery (such as the 1.8T). It may do both, one or none, I would not try it though, even if you do same a few cents.

QCRAZY

..gas milage will be affected if you use a lower octane fuel! You can use as low as 87 octane without causing any problems with the motor(I don't recommend that). However, the lower your octane the worse your performance and gas milage!

Modern cars have knock sensors that retard the timing of the engine to allow you to use a lower octane or if you get a bad batch of gas. If you constantly use lower octane gasoline you will wear out your knock sensor faster and then damage to the engine will occur!!

I would only use lower than the recommended octane if you can't find the proper octane for your car. In the US and Canada it shouldn't be a problem finding proper octane!!!
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Andrew

DaveN

It really is just a microphone.

lja36

knock sensors and computerized ignition that can retard timing only have a limited
range that they can retard. yes, the car is advertised as being capable of running
on 87, but think about what's happening in the engine: the spark fires at a later
point in the combustion cycle, which mean that you have less complete combustion.
the engine runs rougher, there is more waste heat generated (will tax your
cooling system if you're hauling a heavy load), and you will generate more
carbon deposits. if your engine management system runs out of retard it
will start pinging. of course modern cars like the a4 have enough built in tolerance
to handle cheapskate owners but don't kid yourself into thinking that you are being
kind to it.

Lou33

If you have a stock 1.8T or 2.8, I doubt that using 87 octane will affect your performance even one micron. I The bottom line is try it, if there is no difference in performance you will have nothing to loose.

I don't have my audi yet, but I have a '91 eclipse 2.0 turbo, a very quick car. The owners manual specifies 91 octane. I have been using 87 octane since I bought the car, and there is absolutely no loss of performance or gas milege. The engine has 105,000 trouble free miles.

Many people seem to think that a higher octane gas is a "better" gas. It is not! It is simply formulated to prevent knocking in certain engines. Usually older engines or very high performace modified engines. If your car doesn't knock or loose perfomance then you have absolutely nothing to gain by using higher octane.

iceman

I'm also wondering why?

cen

It seems that most arguments against lower octane fuel focus on transient conditions.

QCRAZY

When current flows through to retard the timing it generates heat....which generates resistance...which generates more amps....which makes the knock sensor work harder!!! Harder working shorter life.....I don't know how much shorter the life but shorter nonetheless!!!
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Andrew

QCRAZY

..octane is better on a turbo. The richer the exhaust the smotter the turbo!!! You just wasted 105,000 miles not utilizing your car to it's potential.

But at least you won't know...you never put good gas in. Good thinking.....what you don't know can't hurt you!!!
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Andrew