87 goes away faster then 93 during same driving conditions on my car. Also feels a bit sluggish with 87. Is there a reason for this? From reading the threads, I understand that 93 is a waste of money for the VG. Thank you.

 

Well, I'm sure a lot of guys are going to disagree with me on this one but I'll throw my two cents in. The Octane rating comes from a scale of 0-100 with 0 being a very combustable form of gasonline and 100 being a more stable form of gasoline. Essentially the lower the octane number the lower temperature that is needed to ignite the fuel. There is more to it then this of course, but that's a quck summary. Feel free to disagree...

So, why the higher octane levels then? The higher octane level of gas sold at the pumps are for engines that operate at higher temperatures or pressures and thus need a fuel that can avoid preigniting (pinging). These tend to be newer engines or turbo charged.

In cars like a GXE with the VG (not sure what the octane is for the SE) the recommended octane I think is 87. Anything higher is throwing money away because the car doesn't need it. The operating temperatures and pressures that the VG produce are not enough to cause pinging with the 87 octane fuel.

So, performance wise, there really isn't any difference in the fuels. I one time read that lower octane fuel actually has more "energy" in it then higher octane stuff, but I can't confirm this scientifically. At anyrate, the only reason why you would see a benifit in running higher octane fuel in the VG is if your engine for some reason is preigniting on 87 and the computer is retarding the timing and thus killing performance. To me this says that your engine has some issues if it can't run 87, maybe you advanced your timing to much, maybe there is some buildup in the cylindars or something. At anyrate, I say the reason people think 93 is better is because the 93 is actually just covering over a more sinister problem perhaps.

So, bottom line, if your car isn't pinging on 87 then don't bother paying the gas man an extra 10 or 20 cents a gallon cause he's going to be laughing all the way to the bank. If your car won't run on 87 then you probably have some problems else where.

By the way... I think in California the octane levels are 89-91-93, so I guess wherever I said 87 octane in this post replace it with 89 if it's more appropriate. Or better yet, just stick with what Nissan recommends which I believe is just the lowest octane rated gas.

That's my 2 cents...and sorry for the bad spelling.

 

just too clarify a point or 2.

lower octane takes less spark to ignite and burns more easily.
octane is a measure of a fuels resistance to burning.


NO POWER is gained from running higher than suggested octane ratings.

 

Thanks guys for the info. So maybe the reason it takes me longer to burn up the 93 and it lasts longer is because of the higher octane compared to the 87 burning away quiker since its easier to burn. Correct? Thanks.

 

Well, I'm going to have to disagree with your hypothisis there. The amount of fuel that is sprayed into the engine during a cycle is the same no matter what Octane level you are using. Check your timing, it's probably so far advanced that the computer is retarding it and thus killing performance and mileage. Or you might have so much carbon buildup in the cylinder or plugs causing the 87 to run worse because it's preigniting. Try pulling the plugs and seeing if they have a bunch of crud all over them.

As said before, a properly maintained and well running Maxima will not run any better on higher octane gas. Since yours is apparently doing so, you have problems elsewhere. Just my two cents.

 

Probably.. I did run with 3 bad injectors for about 10,000 miles. Changed all 6, but you really think the damage has been done? Something got messed up then that I don't know about.

 

If you use high octane with a VG, there is a slight increase in performance. The timing will automatically advance to take advantage of the higher octane fuel.

It clearly states in the owner's manual on page 9-2 or on the very last page under Gas Station Information -

Recommended fuel:

VG30 engine models

Unleaded gasoline with an octane rating of at least 87 AKI (Anti-Kock Index) number (Research Octane Number 91).

For improved vehicle performance, the use of premium unleaded gasoline with an octane rating of at least 91 AKI number (Research octane number 96) is recommended

Not sure how much improvement is in the top-end, but I feel it mostly the mid-rpm range.

Keep in mind, not all engines are like the VG. Many engines that specify regular unleaded don't get any performance benefits from high octane fuel as the engine is not designed to advance the timing to take advantage of the high octane fuel properties.

The highest octane gasoline I can get around here (Seattle area) is 91, so I cannot say if 93 would run even better than 91 octane.

 

check your knock sensor, if you get crappy power in the lower rpms under 3000 and bad gas mileage then that is most likely the problem

 

...and tst drive with a resistor using hihger octane. I did get 20% better mileage like snap on (=bad KS):

 

lmao... wiking u got a lot of tricks up ur sleeves for these cars. what resistance is that resistor u got in there?