Were his lips moving?

 

FUEL RECOMMENDATION
Use unleaded premium gasoline with an
octane rating of at least 91 AKI (Anti-Knock
Index) number (Research octane number
96)
If unleaded premium gasoline is not available,
unleaded regular gasoline with an
octane rating of at least 87 AKI (Research
octane number 91) can be used.
However, for maximum vehicle performance,
the use of unleaded premium gasoline
is recommended.
CAUTION

Some good comments to help you better understand why you should use 91 or higher:

>>>>The knock sensor detects -- that's right -- "knocking" (also known as
"pre-ignition" or "pinging")! Knocking is bad for the engine, and it often
results from using lower-than-recommended-octane fuel. So when your cheapskate
husband puts regular unleaded in the Maxima, the knock sensor kicks into action
and retards the ignition timing to protect the engine.

>>>Retarding the timing prevents the knocking, but it also reduces the
engine's power, decreases fuel economy, probably increases the emissions, and
may lead to a buildup of residue on the valves. So it's not an ideal situation.
It won't hurt the engine if you use regular gas occasionally, but it prevents
the engine from performing at the specifications at which it was designed to
perform

EDIT: I WAS INCORRECT ABOUT THIS RATING, IT DOES DIFFER FROM YEAR TO YEAR ON THE G AND BETWEEN AUTO/MANUAL AND COUPE/SEDAN, SEE POST #52 FOR CLARIFICATION. THANKS TO OKSTATEG35
Yes, he did, sort of. You should not be putting less than 91 in any VQ30 or VQ35 engine. This is clearly documented and any dealership that has half a clue knows that full-well. The service side of things would never tell you it's ok to run 87, the saleman probably did simply to sell the car, they'll say anything, and also, you're taking advice from someone who is NOT a Nissan Technician.

Of course, you CAN run less than 91, so he wasn't fully lying to you, but the car is not going to run the way it's SUPPOSED to. And considering that the price difference between the 87 and 91 only accounts to under $3-4 normally on an entire tank, it really makes NO sense to run less. The fuel savings you'll get from running the PROPER octane rating will outweigh this anyways, in the long run, you'll actually SAVE money putting more 'expensive' fuel in.
There's also some level of confusion in the owners manual because it's rated as 87 AKI being the lowest you should put in, which is actually different than 87 OCTANE. I personally need to dig into that deeper to clear it up for myself because I think I always misunderstood this as well. If I'm reading it correctly, Nissan is actually saying that 91 Octane is the LOWEST you should ever put in.

 

^This

 

That is great info.

 

Higher octane gas will not make your engine run cleaner. At any given station the detergents/additives are the same across octane ratings. Across different gas stations the additives will be very similar, the EPA regulates fuels and fuel additives.

The purpose of higher octane is to prevent the fuel-air mix from igniting under pressure instead of igniting when the spark plug sparks at the appropriate time.

Early ignition is a function of the pressure, temperature, and chemical properties of the fuel-air mix. However, I believe luxury car makers in particular recommend higher octane fuel for another reason - marketing. Luxury car consumers feel like their car is extra special if it needs special gas and that helps sell cars.

I fill up with 87 in my 06 AT G sedan and have absolutely no concern about it negatively impacting my engine.

 

As people have said, higher octane rating related to higher activation energy required to start combustion. e.g. higher temperature and/or pressure needed. Most effectively in cars this will effect the compression ratio. The higher the compression ratio, the more energy you can get from the carnot cycle, which means more hp and/or mileage out of the same displacement. That's why sports/luxury cars use higher octane, because people focus more on hp than what gas you put in, whereas economy cars sacrifice the hp for 87 octane gas. You can run different compression ratios with the same engine block, so i'm not quite sure what the maxima VQ uses as gas, but the g35 definitely is designed for 91 octane (stupid cali) gas.

For a production car of course they leave a buffer to where knock will occur. They want to guarantee no knock at all. If you drive short distances and are gentle on the engine, it's completely possible that you get no knock with 87 octane on the vq engine. But it probably will knock if you heat the engine up/drive it hard.

This basically says it better and more accurately than I can:
http://en.wikipedia.org/wiki/Octane_..._octane_rating

 

For someone who seems informed the fact that you're running 87 surprises me, especially considering you think it will make no difference.

FYI, octane rating is not directly related to COMPRESSION RATIO as some seem to think, it's actually just related to timing. The higher the octane the tighter the timing can be, it allows more adjustability and allows the timing to be set at more optimal ranges for fuel economy, power, etc, basically it allows them to get MORE out of the engine, and have it run more efficiently.

Running lower octane retards the timing, resulting in poor fuel economy, lowered performance, and higher emmisions. Plain and simple.

 

Deff premium but W/E you do just don't EVER buy mid grad gas. I know some people that work for oil and gas refineries and they said that unleaded and mid grade is pretty much the same stuff.

 

Spend the extra 3 dollars and 42 cents more on premium gas and have the piece of mind. The VQ operates best on premium gas, plain and simple.

 

93 isn't even available where I live. I always use 91 but I might try 89 because some people claim to get better mileage with it however, the power might be reduced.

 

all vq's require atleast 91.

 

mid-grade is just a blend of 87 and 91. The issue is it's not regulated well, the actualy owner of the station could tamper with the mixer.

Also, there's an argument that about 60% of gas stations's 91+ is actually so old that it's lost its octane rating, and is actually more like 87-89 anyways.

This is why using the same station, that you know gets premium often is highly recommended.

 

I normally use 87 and sometimes 93 or 91 and I notice no difference ever. But I guess after reading some of these posts I'll start using 91.

 

Inside your gas door it tells you to use premium and it's written the same way inside your owners manual. Just because Mom runs 87 doesn't mean you should, it's not the same car....
Gary

 

What a gamble w/ the 87.