We need that oil engineer to check in here again. Since he has yet to do so I'll try recap as much as I remember.

Gas is a commodity and sold in bulk. Everybody gets and uses the same stuff. It is possible to go to a refinery owned by any brand and see trucks from all the others filling up. They then add the brand appropriate package which was reported as being an incredibly small amount of whatever the hell it is.

Doesnt matter what octane you use, economy remains the same. Higher octanes do not add power and have no more energy in them per gallon than lower octane fuels.

Higher octane fuels are more resistant to detonation. This allows for adding compression and or timing before getting into detonation increasing power output of any engines that do take advantage of it.

A summation is that unless your car has the compression and or timing that makes higher octane fuels necessary then you gain nothing by running a higher octane fuel in it.

Our cars do require high test to run at maximum performance. If knock is detected (and it will be if you go WOT on low octane gas) the car is put on the low octane tables and a great deal of power is lost at WOT.

Any mistakes in this post were mine, the oil field chemist was the legitimate article and knew his stuff. I believe however I have the basics right.

 

I've experimented with both regular and premium to see if there is any difference in gas mileage and performance. I get the same MPG with both octane levels, no difference at all.

My general rule of thumb is that since I can drive my car year round, I will run regular during the winter and cold months. Cold months for me might get down to 40 degrees and I have no snow to deal with. When summertime rolls arounds I start using premium because the possibility of pinging is greater when the temperatures go up. Also during the summer with nice whether, I'm more likely to drive the car more aggressively than on a cold winter day when the streets are cold and damp. Why do I need premium (top performance) on days like this? That's just asking for trouble.

I say if you can save a few bucks on gas, why not do it. It leaves more for other mods you might want to do.

Finally I'll tell you that the highest octane I can get in my area is 91 so there's not a big jump from the 87 octane of regular. Perhaps if I could actually get 93 octane, I would see some differences.

 

It will get better performance and mpg with premium, and you are better off just using that imo.

 

If you're concerned, and you have good dealer technicians, you might have your dealer look at it. Like you, our premium octane is 91 octane, and I have noticed no pinging at all on my 2006. You might also try another brand of gasoline, preferably a Top Tier brand...I have good luck with Chevron (hate the company; love the gasoline).

Your PCM should be adjusting timing to minimize pinging if the sensors are operating properly. A very light ping (much like injector noise) only means the PCM is keeping the timing on the razor's edge to maximize power. Actually, the usual pinging heard is pre-ignition and not detonation...Detonation is a much louder, heavier, and more destructive process than pre-ignition.

 

25,000 Miles @ 18MPG == 1389 Gallons @ .20 difference for premium = $277.00. For that small a differential over that number of miles, why worry about it? Stick with premium and enjoy the ride!

 

The engine was designed to run on high test. In the rare instance where only regular is available you can get by. If you run regular all the time then you risk engine damage on a $50k car. When running regular you rely on the computer to retard the timing properly and the knock sensor to function flawlessly.

 

Bull S*it ! What's next ? I shouldn't buy my oil at Wal Mart because it'll be in a Wal Mart bag ?

 

So he will have the down stroke saved for his next Vette.

 

Are you sure it's not your teeth chattering ?

 

 

Freeze up ? Vapor lock ? You've met my former g f I gather.

 

Depends, Jack Daniels or Jim Beam ?

 

And you have an engineering degree to back up that statement ?