BlueDog

found this story in Readers Digest that my wife was using as an arguement that I didn't need to use the top shelf fuel for the Audi. We all know what the answer is, but are these people smoking crack?

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Your owner's manual may recommend premium gas, but is it really necessary?

By Karl Brauer

From Reader's Digest
January 2006

Q: Can I use regular gas even though my owner's manual recommends premium?

A: Yes. Regular gas is actually fine for most cars on the road today, since only a small number vehicles (like Cadillac Escalades and Dodge Vipers) have high-compression engines that require premium gas.

As many as 30% of Americans spend an extra 15 to 20 cents a gallon ($100 or more a year) for high octane. Sure, in cars where premium's "recommended," you may get slightly better performance from your car, but the increase is usually too small to justify the higher cost at the pump. If your manual doesn't specify any type of gas, the car was made to run best on regular fuel, and premium won't boost performance one iota.


Karl Brauer is editor-in-chief of Edmunds.com.<ul><li><a href="http://www.rd.com/content/openContent.do?contentId=19420">Article on RD.com</a></li></ul>

Petethepug

I just saw an ad on TV telling me to go to edmunds.com to see all the chevy vehicles that have discounts. Hey, look at the article that Karl Brauer, editor-in-chief of Edmunds.com wrote. Maybe I will buy that Vette if I can run Calif. 89 octane gas and save .20 cents a gal. Wait...was that a Viper or a Vette that can run on regular? I'm just having fun making up conspiracy theories, don't mind me.

Rally_nutcase_1982

Here is what I would argue: it ain't no Chevy or Chrysler ;-)

Never below 92Oct, the Carbon build up on Valves and other engine parts can be more costly and damaging compared to saving 100 bucks a year on gas.

Audi doesn't put these recommendations in the cars manual because they get gazillions of $$$ from the Petrol Industry. It is the sophistication of the engine that determines the use of good fuel, IMHO.

SpeedTriple

drive bi-turbo charged cars. Generally speaking, any car using forced induction should use the harder-to-burn premium stuff to prevent detonation or knocking (compressing air increases intake air temperatures). Your allroad could retard the timing but it does it to prevent knocking. It is true that running the lowest octane possible is best because you actually get more BTUs out of easier to burn gas. For example, I use 91 in my allroad and supercharged A4, but 87 in my v-twin bike.

dug01

Exactly how does reg gas cause carbon buildup??

Rally_nutcase_1982

Build up happens through fuel that is not consumed and transformed into carbon monoxide (CO) and hydrocarbons (HC) emissions.

The carbon also begins to build up inside the combustion chamber (cylinder walls, the top of the piston, head, and exposed parts of the valves).
This process is called "agglomeration," which means forming a mass from particles that retains its individuality. The more carbon that builds up over time the less efficient the engine becomes. As the engine becomes less and less efficient it produces more and more unburned fuel or CO and HC, which speeds up the agglomeration.

Better, or higher Octane Gas will help to ensure a "cleaner" firing sequence due to higher Temperatures. That will slow down the process of agglomeration and keep the engine in better shape over a longer time.

Good enough? ;-)

SpeedTriple

you run the risk of detonation and pinging. To counter that, the ECU will dump more fuel to "cool" the engine down, causing the air-fuel mixture to turn rich. Excessive fuel means more deposits. That's why people who drive short distances often suffer from carbon buildup. When you start your car in the morning, it runs rich to heat up the catalytic converters. However, the engine is still cold and so the fuel doesn't burn efficiently. Lugging the engine can contribute to this problem, among other things.

oskidunker

nm