are any the A8s FSI?
12-03-2007, 12:32 PM
#12
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Really? To save $400 / yr you'll risk the reliability of the engine in a $70k car?
Just a note to those out there considering regular, the cars have knock sensors so they won't ping with lower quality gas. Audis and other luxury cars are tuned to run on high octane and really 93+. This is especially true for FSI and Turbo vehicles.
12-03-2007, 04:43 PM
#13
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Yessiree
Since I plan to put 250,000 miles myself on this car (it had 56,000 on it when I bought it off of a high mileage two year lease), I figure I'll save $3000+ over the life of the car using regular. That will help pay for PM items and insurance. The 4.2L engine has four oxygen sensors and IIRC, two knock sensors so they will help me just fine.
My old 1987 5000CSQ which was Turbo and 91 octane was listed as the minimum recommended. That was for the first two months of the eighteen years I owned it and never had a fuel system or mechanical engine problem when I donated it to charity with 286,000 miles all put on by me. It accelerated no different for me with either fuel. I was not using a stop watch so i'm sure there were a couple of tenths of a second difference though. When driving through the Rocky Mountain passes, I did use the Western States 91.5 "clean" premium in the late 80's & early 90's
Sticker was closer to $77k on my A8L as it has a lot of the options
My old 1987 5000CSQ which was Turbo and 91 octane was listed as the minimum recommended. That was for the first two months of the eighteen years I owned it and never had a fuel system or mechanical engine problem when I donated it to charity with 286,000 miles all put on by me. It accelerated no different for me with either fuel. I was not using a stop watch so i'm sure there were a couple of tenths of a second difference though. When driving through the Rocky Mountain passes, I did use the Western States 91.5 "clean" premium in the late 80's & early 90's
Sticker was closer to $77k on my A8L as it has a lot of the options
12-03-2007, 05:01 PM
#14
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See now, I go the other way and pay a hefty premium to have 97+ octane fuel delivered to me.
Gassing up is almost painless once I find a long stretch of road to really open her up and join up with the KC10 supertankers for some inflight refueling.
12-04-2007, 02:34 AM
#15
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Re: Really? To save $400 / yr you'll risk the reliability of the engine in a $70k car?
At the first sign of ping, your ECU will start to pull timing back. In other words, it has to ping in order for ECU to pull its timing back for safe operation.
As we know, car is tuned for 91+. It just means the car will run better with premimum fuel. Anything less, car will just pull the timing back, losing some power in the process. And unless you are taking the car to track or dyno, that loss should be negligable.
But as for me, I always put the best fuel I can find, usually 93. I even put Techron every a few thousand miles as well. For a very simple reason...
If I wanted to save money on fuel, I would have bought a Prius.
As we know, car is tuned for 91+. It just means the car will run better with premimum fuel. Anything less, car will just pull the timing back, losing some power in the process. And unless you are taking the car to track or dyno, that loss should be negligable.
But as for me, I always put the best fuel I can find, usually 93. I even put Techron every a few thousand miles as well. For a very simple reason...
If I wanted to save money on fuel, I would have bought a Prius.
12-04-2007, 05:27 AM
#17
AudiWorld Super User
Speaking of gasolines
When I say cheap, I sould have said I use Regular (87 octane minimum) but I only use brand names such as ExxonMobil, Chevron, Sinclair, Shell, Marathon, Sunoco or BP which have the full blend of additives to prevent internal corrosion. Hopefully I'm not dealing with unscrupulous fuel station owners who add water to their gasoline.
When I was a kid, during the late 1970's fuel crisis, I remember being at a Martin gas station in the ghetto in Detroit and watching the owner take a 3/4" commercial hose hooked to a water spigot on the side of the building and put it right into one of the underground tank filling lids and turning on the tap. As looked at him he said "A little water doesnt's hurt anything". It was summer but that winter I remember having the glass inline fuel filter becoming a chunk of ice on my old VW Super Beetle causing a no-start CONdition. And, I was no longer buying fuel at the Martin station noted above.
This was at the time when the mechanical pumps only went to 99.9ยข per gallon so they put stickers on the pumps saying "Price per half gallon" and "Half sale price".
When I was a kid, during the late 1970's fuel crisis, I remember being at a Martin gas station in the ghetto in Detroit and watching the owner take a 3/4" commercial hose hooked to a water spigot on the side of the building and put it right into one of the underground tank filling lids and turning on the tap. As looked at him he said "A little water doesnt's hurt anything". It was summer but that winter I remember having the glass inline fuel filter becoming a chunk of ice on my old VW Super Beetle causing a no-start CONdition. And, I was no longer buying fuel at the Martin station noted above.
This was at the time when the mechanical pumps only went to 99.9ยข per gallon so they put stickers on the pumps saying "Price per half gallon" and "Half sale price".
12-04-2007, 05:38 AM
#18
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Re: Really? To save $400 / yr you'll risk the reliability of the engine in a $70k car?
I want to drive in comfort with lots of room and save on fuel. I've come pretty close to finding the perfect balance.
12-04-2007, 06:28 AM
#19
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They can't without significant chemical sleuthing and some luck.
They can, however, detect if significant pre-ignition has occured. Proving it was due to the gas and not some other engine management failure is more problematic.
Bottom line is that most if not all manufacturers design their vehicles to survive on 87 octane. Theoretically, it should even improve your mileage. I used to run mid-grade gas in my 1990 Taurus SHO for long trips to boost mileage. That motor was running strong at 160k miles when I sold it.
On the RS6 forum we are currently in a "whats the benefit of 100 octane" thread.<ul><li><a href="https://forums.audiworld.com/rs6/msgs/38340.phtml">100 octane available in SF Bay area</a></li></ul>
Bottom line is that most if not all manufacturers design their vehicles to survive on 87 octane. Theoretically, it should even improve your mileage. I used to run mid-grade gas in my 1990 Taurus SHO for long trips to boost mileage. That motor was running strong at 160k miles when I sold it.
On the RS6 forum we are currently in a "whats the benefit of 100 octane" thread.<ul><li><a href="https://forums.audiworld.com/rs6/msgs/38340.phtml">100 octane available in SF Bay area</a></li></ul>
12-04-2007, 06:32 AM
#20
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Mileage and Performace Test
Last winter on a long road trip through the Southwest with my 2006 A8L, I experimented with 87 and 92 octane fuel. I changed fuel type every three tank fulls for about 2,500 miles.
87 octane gave me an average of 23-24 mpg, 91-92 octane averaged closer to 26-27 mpg. I could not detect any difference in smoothness of operation between grades. Acceleration on 87 octane fuel was decidedly reduced; most of this test was at an altitude of 4,000-7,000 above sea level.
Conclusion; I went back to using the high-priced spread. The cost savings were minimal at best, and I enjoy the better performance.
87 octane gave me an average of 23-24 mpg, 91-92 octane averaged closer to 26-27 mpg. I could not detect any difference in smoothness of operation between grades. Acceleration on 87 octane fuel was decidedly reduced; most of this test was at an altitude of 4,000-7,000 above sea level.
Conclusion; I went back to using the high-priced spread. The cost savings were minimal at best, and I enjoy the better performance.