dokebi1221

87 octane on A8???????....80 - 90k car (NEW) eating junk food....

kbaum17

Had a 1997 A8, 4.2. Had 83k miles when I bought it, no point in spending the outrageous amount of extra money just to have 3 more octane. ALWAYS put regular unleaded (87 octane) in it. Sold it with 160k miles...not a single problem with the engine...sounded the same with the same power and smoothness as the day I bought it.

But, yes, there is a technical difference in how ta neeeew engine deals with the different octanes. But, what you gotta understand is that, when an engine gets more than, say, 75k miles on it, it just isn't going to make a huge a difference one way or the other.

..and I have heard others say, to the opposite, that they have put high octane (91-92 octane) in a high-mileage vehicle that was designed for low octane, and the vehicle ran better in its old age with the high-octane. My point is that, for the most part, people are just bonkers on the whole octane issue. the MAIN thing is that, when the car is newer and younger, you SHOULD put in the recommended octane. But, when it is old (over half the life gone), it is not such a big thing to worry about the recommended octane.

kbaum17

97% of low octane gas (85-87 octane) sold in the USA has ethanol in it...and, in some states, you can't avoid ethanol even in the Premium grade (91 or higher).

Ethanol is the biggest joke placed on the American consumer in the last 20 years...and one of the worst examples the govt. supporting one group while blindly ignoring other groups. Ethanol benefits only 2 groups (farmers and companies that are part of the ethanol manufacturing supply chain, such as ADM)

mishar

You are wrong. Older cars inevitably have carbon deposits that act as glow plugs causing premature ignition and detonations. With low octane fuel it just gets worse. Knock sensors will detect detonations and retard ignition in order to prevent them. That will lower engine efficiency and annul, or even reverse, fuel price difference. Worst thing is that engine will tend to bring ignition to the designed mapping all the time and retard it again when detonation is detected. So there are detonations constantly.

In my opinion there is no point in driving $100K car and saving peanuts on fuel. That's just like not washing it ever. It works dirty just fine.

mishar

First question is: what's wrong with ethanol? Up to 10% in my tank, or up to 45% in my glass sounds just fine to me.

milellie111

"Hey, how about i go sign up on Audiworld forums then post nonsense in half year old threads"

kbaum17

Exactly what is nonsense about my post? Exactly what??

I gave you an example, a real example, of how lower octane made no difference whatsoever in the performance of engine over the course of 80k miles to 160k miles. And I could give you another half-dozen similar examples of friends of mine...and even my mechanic (who has easily owned over a dozen Audi's).

Also, I have an idea that folks like you will like even better: go into half-year old threads and post nasty remarks.

---as if the age of the tread has an relevance to anything.

kbaum17

Believe me, I understand the basics of the arguments of higher octanes. And I also understand that "octane levels" is a subject that some take to heart. And I appreciate your feedback and I understand what you are saying. Your explanations help. But, I am not wrong in what I am saying. It iiiis possible for both of us to be correct. You are talking design and theory and what is probably best. And I don't disagree with what you say. However, my point was about it not making aaaaas biiiig of a real world difference in an older car. You say that, in fact, the older the car, and the more that person uses lower octane, then the worse the problem will be. Perhaps, but not always. Other factors come into play also. Regardless, maybe that is how it should be. Just like we 'should turn off our phones during take-offs and landings' and maybe having phones turned on does make some sort of difference. But, when you have a car that has 95k miles on it, a driver is hardly going to notice a big difference with the higher octane...nor will they notice a discernible downgrade in performance by using the lower octane. Perhaps they should, in theory, but most wont notice it. I know I didn't and still don't. That was my point. So, I think we are both correct.

As for spending the little bit of extra money: a 2004 - 2006, just isn't a new car anymore and not worth $100k. I wish it were different. I try to use that logic on my friends when I tell them what I paid for an item: I tell them "Look, I got a $300 pair of shoes". They always say "What did you pay for them?" "$50", I say. "Then you got a $50 pair of shoes."

My point is that, sure, if you can afford a $100k car, then why not put in the extra cents. But, if you have a car with 95k miles on it and it is only wooorth $15k, and it doesn't make a discernible difference in reliability, performance, and longevity, then why waste your money on the higher octane?

kbaum17

Also, many gas stations in the US only have room for 2 storage tanks in the ground. This means they really only have 2 different grades/octane of gasoline. But, they list 3 grades at the pump for sale. It would be illegal for them to sell a lower octane than you are paying for, so their solution: one tank in the ground is for the lowest grade (you get what you pay for). But, the 2nd storage tank's gasoline is sold has medium and premium grade but it only contains the premium grade in the storage tank. In other words, if you buy the medium grade, you are really getting the premium (but for less money, of course).

mishar

I understand what you are saying. In that manner, why wouldn't you go further? You can save on oil changes. I can ensure you that you will not see any difference if you only add some oil when needed. No changes, filter included. You can also save big buying used tires.

There are multiple ways to make your $15K car a junk yard car.