HaveBullDogWillTravel

My feelings might offend a few.
Many owners of premium cars that use lower octane fuels instead of the recommended 91+ are
1. Uninformed. (haven't RTFM)
2. Informed and can afford it but choose not to because they're short-sighted and cheap.
3. Informed and are leasing and figure it will be the next owner's problem.
4. thinking that using high octane fuel is pointless as they cannot perceive any worthy difference in performance or fuel mileage and consequently, a waste of $$$.
5. Other

UrbanExtant

I couldn't agree with you more. Both of our cars are leased, and we took the time to break them in appropriately, make sure to use the correct gas in them, and have all maintenance performed because when we turn them in we want the next person to own them to get the same enjoyment and satisfaction out of them that we have. I wish everyone was that way.

actoraine

But that's just a random web site...

Also, you may want to check out the third paragraph of #3 here
http://www.smartmoney.com/spending/r...ell-you-19750/

I think the gas stations matter much less than you think.

The G Man

Shell V-Power and Chervon are suppose to be the best, since there is no Chervon here in MA, I use Shell V-Power.

Epicurus88

No, this isn't a random website.

If you bothered to read the manual that came with your Audi, you would find that this is Audi's official pre-approved list of gas retailers.

mpraju

I have been using Shell always. In Dallas Shell is actually cheaper than any others because of the 10-15c per gallon discount with a Krogers shopping card ( if you buy $100 worth of stuff a month at Krogers)

Xpri

I had significant carbon build up in my last A4, one of the reasons I decided not to keep that car. My troubles started at about 15k miles, I had been mostly using Mobil up to that point, the gas station on my way to work, but then switched to Shell and Chevron. I'm not sure it made a huge difference as I continued to have issues for the next 30K miles but the damage may have been done by the time I switched.

The carbon build up used to cause a misfire when cold and the MIL light would then go on. This was always worse when it was cold and during the winter months. One thing I noticed was that this often happened if the engine had not been allowed to warm up, for example, if I had pulled the car out of the garage to wash it and then returned to the garage afterwards. The next day I would almost always get the MIL light.

I always use Shell or Chevron in the Q5 and so far no issues.

okietawney

Hi, what are the first symtoms of the build up? Does oil change interval play into this at all or strickly a gasoline issue?

thanks

HaveBullDogWillTravel

This situation can occur with most any vehicle. A non-start/misfire is not uncommon if a car is started cold and then shut off before the enriched mixture is burned away. Left for the night the additional enriched mixture from yet another cold start will foul the spark plugs and...sputter, sputter, sputter. Carbon build-up may exacerbate this problem.

ELEVENS

Good fuel only delays the inevitable. It's a design issue with direct injection. Here's one of my intake valves in my RS4 at 33,000 miles. It took me about 12 hours of dirty, manual labor the clean the motor up. It showed no misfires or cold drivability (and therefore Audi won't service it for you) but was down about 25 horsepower. The carbon resulted in 8-12 degrees of timing retard even in cooler weather using Shell 93 octane (R+M/2). I was blending my own fuel for a good long while to restore the timing issue until I cleaned the carbon out myself. Thanks Audi!