****ty foreign policy is one of the main factors.

Until we stop relying on thugs in the ME and South America, it'll just get worse.

 

I just filled up my G this week. Sitting there at Sunoco....the price of regular was 3.45/gallon, the price of 93 was 3.75/gallon. So 30 cents/gallon difference, even if the car took a full 17 gallons it would have amounted to 5.10. I dont fill up often at all, but even if you assumed one fillup per week, you are looking at 265.00 per year.

Honestly not worth the savings, if you ask me.

As far as can the car run better with different octanes, its all in the fuel maps that Nissan/Infiniti installs. I know my old Accord only had a map for up to 89 octane, so using 91 was a waste (and it was unclear if 91 caused a failsafe and made the car run like it had 87). I dont know what maps are in the G, but Im guessing they have one for 91 octane. It would be interesting to know if it takes advantage of 93 octane or if 91 is the highest it expects.

 

I had an 04 G35. Manual called for 87 and that's all she got. Designed for 87 and you put 91, you're wasting money. THE END.

Scientist my rear end. 87 vs 91 octane will not boost your mileage. It is an AKI. Anti Knock Index. Federal Trade Commission reports state that using higher octane gas in your regular car does not improve gas mileage. Higher octane is only recommended for cutting down on engine knocking. Higher compression, higher octane. It has ZERO to do with freakin' fuel economy. Jesus, Mary and Joseph.

I use 91 octane in the G37 because the manual calls for it and I don't want my engine knocking when I stomp on the gas. That is all.

 

The knock sensor sends a signal to the ECM when it senses a knock and the ECM retards the timing to eliminate the knock. This does lower power and hence fuel mileage. In a G37, you WILL get better mileage using premium fuel.

 

I agree.

 

8) Yes, there were so many holes in this "experiment" one could drive a car through it! I'll ask my wife if I can buy 6 G37s and drive each to CA. I'll let you know what she says.

I should note the car was a BMW and requested premium gas. It is entirely possible (indeed, plausible) that rather than receiving an efficiency boost in using 91 octane gas I simply avoided an efficiency loss caused by using 87 octane. It really isn't a controversial result to note you get better performance when using the kind of gas for which your engine was designed.

-Ed

 

Sample size and experiments aside, this is like using tap water instead of windshield washer fluid, and then whining when the nozzles clog up.

I've always followed the manual for every car I've driven since 1991 with no issues. This goes for fuel grade, maintenance requirements, oil SAE, etc. The engineers don't arbitrarily choose an octane rating out of a hat, and anyone that decides to save a few bucks per tank is losing horsepower.

I want every single one of my 328 hp showing up for the party. They were expensive!

 

You can mix 89 and 93 octane to get 91 if the small hassle is worth it to you. I do, why not. ...except when I'm at Sam's Club, they only sell 87 and 93.

 

I remember someone here tried to mix a smaller portion of 87 with larger one of 93 to get the minimum requirement of 91. Props to him but... really?

 

I haven't seen 93 anywhere in Cali. 91 is what most stations have for premium. I went to Costco to fuel up but saw the "10% ethanol" sign and left... well, the joke was on me because I did a little research and found out that "carb" (ca air resource board - a complete fuggin scam) requires ALL CA gas to contain 10% ethanol. Seems they used that to replace the MTBE crap.

I gotta get outa here. People wonder why they get better mileage when they fill up in AZ or NV...

 

Most places in North America use 10% ethanol in their gas.

 

I doubt 10% ethanol adversely affects engine performance much. It is my understanding MTBE was found to be a major water pollutant, the reason why it was replaced by ethanol.