123Audi4me

Does everyone use the recommended "premium" grade fuel in their 2.0T's? A friend of mine has a 2011 Q5 2.0T and said he uses mid-grade and occasionally regular grade with no problems. I currently have a 2001 A4 2.8 V6 and have used mid-grade for years with no problems. We live at an elevation of 5000' maybe that makes a difference. Although at sea level, I never experienced any problems or knocking with mid-grade fuel in my A4. What are the reasons for using only premium grade fuel? My new Q5 2.0T should arrive in 2 months and saving $.10 to $.15 per gallon makes a difference these days. Thanks.

rdA4WtQ5

Your new 2013 Q5 is also a flex fuel vehicle and can also run E85 if desired. From reading posts on other forums the cost per gallon savings are outweighed by the poor fuel mileage. While performance (power) is as good or better than gas it is agreed it could be much better with an E85 specific tune due to the much higher octane although lower energy content. My 2011 Q5 recommends 91 octane in the manual and requires it on the fuel door. I run primarily shell premium 93 octane and have topped off with regular 87 octane on occasion with no perceived drivability difference. Mid grade is 89 octane here and is blended at the pump with it being mostly regular with a little premium mixed in at almost the price of premium. Mid grade is the poorest value for you and the most profitable fuel to sell for the oil companies. I try to stay away from it. Your new engine is designed to run on premium and from a complete combustion standpoint to minimize valve stem carbon I would try to see your octane be in the 91 range for that reason. Hot weather, long steep hills and towing, octane is your friend. My 2 cents.

DennisM

The Q5 is not a flex fuel vehicle.
http://models.audiusa.com/q5/engines#view-all

The car requires high octane premium so it does not make sense to use lower octane fuel to save a few pennies. If saving a few pennies on fuel is a prority, why did you get a Q5 turbo?

Q5 Bob

My 2013 2.0 is a flex fuel vehicle.

I usually run premium unleaded (93 octane), now and then a couple of tanks of mid-grade (89 octane).

JohnBoyToo

While many will say use only premium
(and they'll be along shortly to say -
why did u buy a premium car if you don't want to use premium fuel or it will mess up your motor, or detonation or ....)

I use premium most of the time - because I can, but do your own research and make a decision based on your own needs:

https://www.google.com/search?q=usin...remium+vehicle

basically the mfg's recommend premium because they've advertised their mpg, hp, and torque figures derived with premium and without premium, they will fall short of those numbers... and get sued for false advertising - the ONLY reason they recommend premium

A local radio guy (that is also a national columnist - Ed Wallace) has said for YEARS you don't need premium...

I met a guy who had a dog....
that said I've worked on several gasoline & diesel truck loading stations. This is where the trucks load up to deliver fuel to the gas stations. Every one of them, in several different states, was the ONLY truck loading station for the area. We had different injector systems for the different company additives, but every company used the EXACT SAME GASOLINE. Exxon would get a few squirts of their stuff every 100 gallons, Mobile would get a few squirts of their stuff. Always using the same gasoline.

IMHO

idale

Some are, but not all (there's two 2.0T non-hybrid engines listed on the EPA's site); it's probably used in particular regions or something where FFV is favorable for regulation purposes.


Sure, the base petrol (or diesel) is the same, but the octane is still different between grades, and of course the system is designed for 91 octane. The ECU will retard timing to deal with knock so you won't destroy the engine by running too-low-octane fuel, but of course you won't get the stated performance and it's still best to avoid the engine knocking at all even if it's just a little.

I would try and stick to an octane of 91+ (here in Texas you could 50-50 89 and 93 other than out in West Texas at the higher elevations), but occasional tanks of lower shouldn't really do much of anything. But in the end, it's everyone's individual vehicle so do what you feel is best for yours.

Q5 Bob

I regularly see tankers from the same wholesaler/distributor delivering to all of the different stations in the area. Does each load contain each brand's nationally marketed detergent/additives? Probably, maybe, hopefully. I don't really know.

I agree - Do your research and use what you think is right for you. IMO you can't go wrong either way.

dougnash

With a forced induction car, you need higher levels of octane to obtain the peak performance of the engine. If you pick up a good engineering book, regarding racing and forced induction, you'll see two things which can either kill or elevate an engine's output. Heat & fuel volatility.

The reason why you don't hear pinging, is because modern ECU equipped motors are able to retard the timing and increase the richness of the fuel/air mix, to prevent that damage. But it obviously means that your motor isn't operating as designed.

Any discussion as to the actual methods by which each filling station acquires, and then boosts the octane for each given load of fuel, is up to all of you.

123Audi4me

Thanks to everyone for the comments. Does being at an elevation of 5000' make any difference? I heard somewhere years ago that lower octane fuel could be used at higher elevations.

dougnash

Not sure about that logic. The most important thing to remember about higher elevation, is that the oxygen density in the air drops precipitously. A forced-induction car actually has an advantage, in that the ECU can increase boost, up to a point, to counteract that change. But, the more you compress the air, the hotter it gets. Therefore, you still need higher octane to prevent detonation. Obviously, the ambient air temp also drops as you increase your ascent, but the impact of elevation on air density is always greater than temperature.