2006 A4 2.0T Fuel Choice?

I suspect they recommend premium (91 octane), that's what the recommend for the 2.0T's predecessor, the 1.8T. However, I usually alternate between 91 and 89 in my car with no ill effects - mileage and power seem to be the same....

As far as the chip, for the 1.8T again, a mild chip will get you to

200hp so I would assume the same type of gain (20 - 30hp) would be easy for the 2.0T with nothing radical.....

Dan D '04 A4 1.8Tq MT-6 Central NJ USA

Dan D '04 A4 1.8Tq MT-6 Central NJ USA

Where are you? I'd expect Audi to optimise the tuning for whatever's available in the local market. Here in the UK, the choice I have is 95 or 98 RON. (I can't get fuel as weak as another poster says he uses in New Jersey.) There's a label inside the filler cap door that says that either of my possible choices is acceptable. I use 95 in my '02 A4

3.0.

Peter.

Peter, I live in Lond Island, NY. 87,89 or 92 octaine is available!

... the difference being that octane is measured by MON in the USA and RON in the UK. They are not the same thing!

Never heard of a Lond Island here in New York. I do live on Long Island, though ;-P , and there are even more grades available than that. I've seen 87, 89, 90, 91, 92, 93, and Sunoco used to sell 94, don't know if they still do. However, these are AKI, not RON. AKI is (RON+MON)/2, where MON is the Motor Octane Number. MON is obtained in a similar manner to RON (using a calibrated test engine), but under different test conditions. This number is generally several points lower than the RON, which is why US "octane numbers" tend to be three or four points lower than corresponding Euro "octane numbers".

-- Mike Smith

Ah. I had wondered if something like that might be the case. How do they compare?

Peter.

See Mike Smith's posting for the correct (and more detailed) information!

Depends on where you live.

In Nevada for instance one can buy racing gasoline at the pump. Seriously.

I once filled up a 2000 A4

1.8T with racing gasoline in Las Vegas, then drove it straight to San Diego.

Much to my surprise the mileage improved by 10% and the engine ran quite a bit cooler judging by the coolant temperature gauge.

YMMV of course.

dk

Thanks - that one hadn't appeared on my server when I wrote my posting earlier.

Mike refers to an interesting Wikipedia article, from which I quote: '87 octane fuel, the "normal" gasoline in the US and Canada, would be

91 in Europe'.

So, in spite of the difference in measurement methods, the fuel available in the US does typically have a lower octane rating than that here - I can't buy anything as low as 91. The norm here is 95. Ergo, I still think that motor manufacturers will have to tune their engines differently for different markets if they're to function satisfactorily with locally-available fuel.

Does the higher octane rating of British fuel imply that identical cars would perform better on British fuel than American?

Peter.

No. The effective, in-motor octane number of the fuel is the same, it's just the measurement method is different.

If I give you 3.785 liters of something, or one U.S. gallon, you still have the very same volume.

RON numbers are always higher that MON numbers on motor fuels. I know for a fact that some premium gasolines run 98 RON and 88 MON. I've seen some regular gasolines at 94 RON and 82 MON. They really can diverge quite a bit.

The wiki article is interesting, but the 87 in the U.S. = 91 in Europe is just plain wrong IME.

-- E.P. '95 UrS6

If the engine is tuned to run on a certain octane rating fuel, then it will perform less well on a lower octane rating. A higher octane fuel won't, necessarily, improve the performance.

My RS6 is specified for 98 octane, but with the ability to run on 95 octane with lower performance (as are many recent UK-supplied Audis). Initially I ran with Super unleaded (97 octane). I started using Shell Optimax (~98.6 octane) and the fuel consumption showed an immediate 10% improvement. I have made no measurements of performance, but the car certainly feels better on Optimax.

My A4 Quattro is specified to run on 98 RON. Recently I have been running it on 99 RON fuel and it seems to perform even better and it's cheaper than Optimax.

Have you tried 99 RON fuel ?

Richard

Unfortunately I'd have to go well out of my way to get to Tesco.

95 RON would indeed be higher octane than US 87 AKI (what we call "regular"), more like 90-91 AKI (what we call "mid-grade"). US "Premium" tends to be about 93 AKI (i.e. about 98 RON).

If the car is designed to do so, yes. Otherwise, no.

-- Mike Smith