xfirechief

Last night I filled up with 15 gals. After I looked at the total I noticed I put in the Mid grade stuff. My error, never ran that before.

The good news is it was 40 cents less then the premium which is 93 octane.
Anyone use the mid grade all the time? Notice anything different then using the 93 Oct?

I average 29 MPG with the 93, if I switch to the 89 will I see a big difference?
For 40 cents times 15 gals I save $6 a fill. Times 4 times per month $24 or so. No biggie but if I see no change why spend the extra??

Don Keener

This has been discussed many times in the forum so a search should turn up several threads. Bottom line is that you paid a premium price for a premium car... why cheap out on the fuel and use something below the minimum recommendations of the manufacturer.

Redd

Well, if you're drinking it, 89 octane should work just as well.
OTOH if you're putting it in the car, the results might depend on whether you've got a flex-fuel or turbo engine, and what your driving habits are.

Dalancroft

I was going to say you might be OK if you live at a higher elevation, say, Denver, but your sig says Wisconsin so ... no. Why risk ruining your engine for a paltry $25/month?

_doom

Oh what I would give to get some 93 in CA.

Redd

If he's got the flex-fuel engine, HE CAN'T RUIN IT by using any of the accepted fuels that the engine is designed to run on. And warrantied to run on. Including 89 octane.

idale

Flex Fuel only means that it's able to run E85 in addition to petrol, it doesn't mean that 91+ would no longer be "required" by the manufacturer. I know VAG used to have premium as "required" on all models and they've backed off more recently to "recommended" on a number of models, but I don't know what the Q5 is. The Q3 2.0T is definitely "required" (I had a loaner recently), but I haven't checked any Q5 2.0T or 3.0T fuel doors. The EPA's site lists them as premium, but I could see them doing that for premium being "recommended", so you'd need to go to the source (your own vehicle).

uberwgn

AFAIK, all Audis in the USA will show 91 octane or better:

BillBoost37

I was going to say. The gas door says it all to me.

The difference in octane is usually apparent with predetonation. You may not notice it, feel it or hear it. One day though, you may experience needing a new motor and that is the proof that the manufacturer had enough timing and other factors built in that require premium.

Q5 Bob

I think where some of confusion comes in is that in the owners manual it says something to the effect (I don't have mine handy) you can use 87 octane but may experience reduced engine performance.

Not an issue for me, since I use premium, but in a pinch I wouldn't hesitate to use mid-range which is 89 around here.