Interesting thread! This may be the same as Albuquerque, from October-February we have a clean air additive in all the gas we buy, we are at the same altitude as Denver.

 

I don't know how much of a diff it makes on the G35 (don't have mine yet :-P) -- but as an 02 Maxima 6sp owner, I put in 87 octane and have noticed no drawbacks whatsoever.

The -only- advantage i've seen to higher octane -- is seemingly slightly better mileage. Even so -- i'd have to run a better test with all things being equal (who knows how i drive in any given week, depends on my mood).

Car is still very sprite with 87 octane.

 

Just used premium gas. Don't skimp, it's not a cheap car so it doesn't deserve cheap gas. It just doesn't make sense to me, it says go with premium fuel so why try to beat it?
Big deal you spend an extra 10-20 cents more and will probably cost you an extra $100 or couple hundred dollars a year (depending how much you drive). Spending time in a dealership trying to fix the problem of knocking, pinging or worse worth it?

I think not.

 

If people were to really understand the need for different octane fuels, I doubt you'd go cheap.

There have been a few posts mentioning audible pinging as the result of incorrect fuels, but that noise is more than just an annoyance (it's not always audible, either). The pinging is the result of the air/fuel mixture igniting prematurely; i.e., before the piston is in the correct position. Ultimately, you have a tremendous (controlled) explosion beating hell out of your piston(s). I have personally seen burned pistions as a result of predetonation. And you guessed it, the more powerful the engine, the more forceful the explosion, and the more damage is done.

And yes most (but not all) cars can account for predetonation, but remember the predetonation event has to occur before the ECU can intervene. Some systems are better than others. In the days of old, you could easily ruin a high performance engine in a day. Nowadays, you have systems to help MITIGATE predetonation, but they don't eliminate it or its potentially damaging effects.

I don't have experience with chronic predetonation on newer cars, but the above explanation of what is happening should be enough to persuade you from using the wrong octane. A few posts have done an excellent job of quantifying the 10 cent difference over a tank. Besides, if the cost of gas is a concern, you probably shouldn't have bought a new/newer car, let alone a performance one.

 

I the days of old, I saw an oldsmobile engine that had the hole the size of a dime in a piston from using the wrong octane gas....

 

This has been asked a dozen times before. Just read your owner's manual, it says premium fuel. Enough said.

 

Hmm, fuel costs..oh, the agony. If you can afford to drop 35k on a car what's the problem with spending an additional 20 cents per gallon on gas? This is why I shy away from these forums, ******** abound.

 

That's funny. My owner's manual says I can use 87 octane.

 

How did you know my nuts were numb???

 

So use 87 octane then.

 

Well, I just picked up my 2005 6MT coupe and the dealer filled it up with 89 octane. When I challenged them, they said, "Oh, that's what we've always put in our cars..."

 

In my 05' MT6 sedan, I will use only 93 octane. I also have a 02 Ford Exploder for a company car. (Man I hate to get back in that thing after a weekend in the G! ) Ford says I can use 87 and I have, however, it will ping pretty bad with it. 89 is better and that's what I'm running now. I ran 93 in it for the last 3 years and never heard a sound out of it. It doesn't take much pinging from pre-detonation to burn a hole in an exhaust valve. I see it as cheap (relatively) insurance.

 

Ahhh, the luxury of owning a 2004 sedan. The 2004 is ONLY 260 HP and the book says you can use 87 octane. I have tried it twice. I get slightly less mileage but still good performance with 87. I find no performance or mileage difference using mid grade (89) instead of premium (91) octane. I car poole with my wife. She has a Turbo Diesel VW and gets over 30 MPG. I am hardly using my G, maybe one day per week. Should I sell it?

 

At least not in my 2003 G35 Sedan. I have 25000 miles of experience that proves it. It has never audibly pinged. And believe me, I know what pinging is about as my 2001 Corvette Z06 pings like crazy if it has anything less than 93 octane.

As far as power, I have driven my G35 automatic back to back with a 2005 G35 6MT. Sure the 2005 model had much less miles, but my G35 was not found wanting for power. Unless the 2005 makes much more power on break-in (10K miles in my experience), the power difference is advertised power not road power.

Don't get me wrong. I want to upgrade. I just want the car to be better rather than a more expensive same.

 

I don't mind paying for performance. But when it comes to 91/92/93 octane fuel, I think it's really a personal matter if you choose to use it or not. There seem to be a lot of posters of the opinion that running the G35 (and I only really know about 04s) on 87 octane is harmful to the car. I don't see any evidence to support that conculsion. The Infiniti manual is very clear, for sedan owners use a fuel with a minimum octane rating of at least 87.

Look, I won't tell you what to do with the $4 you've got in your pocket if you don't tell me what to do with my $4.