Originally Posted by OKStateG35

I don't even know where to begin with this. You clearly don't know what you're talking about at all on the subject. Pretty much everything you said is wrong.

It is a fact that octane ratings change by state.

You are saying again, that the OCTANE RATINGS CHANGE, this is not true, the NAME of the 'fuel type' might change (mid-grade, premium, etc), but the actual octane number does not change, it's regulated. Period. What you're saying is just plain confusing.

The requirements for regular and premium change depending on altitude so gasoline retailers change what they sell accordingly. That is why premium is 91 in one state and 93 in another or regular is 85 in some states and 87 in others. As long as you are using the grade level required for your engine in whatever state you happen to be in you will be fine. As far as mid-grade goes, go back and read what I wrote. Since it is a blend of regular and premium it will obviously vary by state in direct correlation to what octane levels regular and premium are in those states. I don't see how any of that information contradicts itself.

This makes perfect sense, now I understand what you're saying. you're talking about the NAME of the fuel, NOT it's octane rating. And shoot, that changes from station to station, not just state to state.

The (R+M)/2 for each grade level is regulated. In other words, if they say they are selling a certain octane level for a certain grade, the gasoline in the tank is required to be at least that level of octane. It is also a fact that different countries around the world measure octane using different standards. The United States happens to use an average of the two most common measurements (RON and MON).

Thanks for this answer, I didn't know that.

I stated that compression ratio is not the only determining factor in octane requirements. It is directly related though.

Semantics, you're right in the context that it's related, I just wanted to point out that it's not the primary reason. that's come up a couple times in this thread I wasn't coming at you for saying it just trying to clear it up for others.

Your quote about not believing what your gas door says is pure gold. Also, my manual specifically says Sedans with 5AT's are required to use 87 AKI gasoline while 91 AKI can be used for improved performance. I'm not sure how much clearer it needs to be.

I didn't say not to believe your gas door sticker. I stated that it's not the be-all end-all. That sticker is put on almost every nissan/infiniti, regardless of the recommended octane rating. The fact is, the owners manual is the place to find the recommended fuel for your engine not your gas door.

If I can't trust what my car specifically says to use what can I trust? I can say for certain it won't be anything you say.

Well, that was sweet of you to say I've never seen a G35 or Maxima manual that recommends anything other than 91, so if there is one, and my conception of this is clouded, I ask you AGAIN, can you please kindly reference this information so we may all be as enlightened as you? Because you're the only person I've ever heard say the owners manual says that 87 octane is the recomended fuel for the G35. If this is so, then we need to know.

Originally Posted by SDGenius

my users manual clearly says, to use at least 87 but 91 is recommended. i hear that may have changed for later models but i can't confirm. although i'm sure you'll be fine running 87 in any G due to the fact that that's what dealerships put in their loaners. my ECU was re-tuned for 91, so that's what i use. on my Wife's G, she puts in whatever, normally 89 though. when i put gas in it, i choose 91 because i'm used to paying for it, so it doesn't bother me.

Originally Posted by TunerMax

Originally Posted by OKStateG35

I have always used 91 or 93 in mine. Good to know that I'm not the only one on the planet whose manual says 87 can be used. Was worried I might have to post a photocopy for TunerMax.

Originally Posted by TunerMax

WTF is a photocopy?

Originally Posted by OKStateG35

Correct. The octane level for a specified grade is different between states. I never meant that the octane level of a particular gasoline changes depending on altitude. Sorry if that was how it came across.

I don't own a Coupe or a 6MT Sedan so I don't know what their gas tank says. Does it really say 'Premium Recommended' when the manual says it's required? That's dumb if so. The sticker and manual should match to avoid confusion.

As for the manual, I already mentioned what mine says. It very specifically states that 87 is required and 91 is recommended for higher performance on 5AT Sedans. Coupes and 6MT Sedans require 91. I have it out in front of me and re-read it just to confirm. SDGenius has also noted that his says the same thing and unless I'm reading it incorrectly, didn't you even reference 87 AKI in post #17?

Originally Posted by TunerMax

Yeah pretty much all of them say that on the door.

And I'm glad you smacked me upside the head with this knowledge. I was confused by the AKI rating, and 91 octane rating comments. Very happy to have found this out because I WAS misinformed, as were/are a lot of others.

If AKI is the rating used in the states as normal octane rating, then the following applies to the 1st gen:

2003-2004 6MT and 5AT SEDANS: 87, with 91 recommended for better performance
2005-2006 6MT SEDANS: 91
2005-2006 5AT SEDANS: 87 with 91 recommended for better performance
2003-2006 Coupe (all): 91

Thanks again dude very nice to find this out!! Sorry again if my post came off rough around the edges

Originally Posted by SDGenius

D@MN Tuner, you've been pissing people off left and right, LOL

Originally Posted by OKStateG35

No problem. That happens a lot on the internet. I like to chime in on gasoline related topics because I've worked in the industry for 6 years and have a little bit of first-hand knowledge. That's not to say I'm an expert though.

Originally Posted by jarvo

race gas..

Why you ask?

because...race car.