adiraval

Dear all, would it be okay to use 89 octane or 91 octane for a 2009 Audi A4 2.0T Quatrro? Many thanks, Adi,

Macallan21

I wouldn't use 89. It's basically the regular fuel with a shot of octane boost.

91-93 is all Premium and fine.

snagitseven

While they recommend premium fuel, Audi's modern engine management systems allow for any grade down to regular. However, be aware that your car's performance will be throttled back. For a $40K+ car, the modest savings of a slightly less expensive fuel grade is kind of like buying a $3000 HDTV and using a VHS recorder for your video source. Yeah, it will work but will you get the most performance out of the investment you made?

Macallan21

Oh, don't do that again. Yes, the car is built to run on 87. It has to be, because of NHTSA. And it can do it.


We ran 91-93 on a Lexus RX350 2007 model for 3 years. Everything worked fine. Ran 87 on it for 2 years, and had 2 O2 sensors, the one that sees the fuel (up top I think) die, a year apart. Switched back to 91-93, for a year now, and no problems. At least at Lexus, that is a $600 repair.


While the car CAN do it, you're running it off spec, and just waiting for the ECU to remap to a different firing sequence and hoping everything mechanical works the same.

stan211

Its never okay to go less than Premium in a Turbo Car. Yes, the engine management will handle the fuel okay, but really whats the point of buying an Audi then? Might as well get a mainstream sedan and poor 87 into it.

Macallan21

I thought the Dodge SRT-4 had a turbo and ran on 87. Mind you, you don't see a lot of OLD SRT-4's still running, but I'm just saying, that a turbo doesn't dictate 91-93.

audiintheblood

go with the 91 octane - better safe than sorry!

dscline

So the moral is: Lexus O2 sensor life span is about 5-6 years. Fairly typical for any car.

OriginalSHARPY

I have a semi-related question. Is it bad for the engine or vehicle in general if you go back and forth between 91 and 94? I plan on using 94 off the start, but sometimes the prices are just to ridiculous and I may drop to 91 for a few fill ups. Is it a better idea to just stick to one? or as long as you don't drop below 91, you're okay?

Thanks

Macallan21

No. Please re-read what I wrote.

1st sensor went bad at Year 4. Same sensor (which is only 1 year old) went back at Year 5.


Originalsharpy, anything about 91 octane will be fine. When you open the gas cap cover, you'll see a sticker that explains the fuel requirement inside there. Where are you from? I haven't seen 94 octane in the Midwest.