Well, here is my experience with different grades of gas. It is a 2001 GXE, manual shift with about 80K miles, everything stock in engine/intake/exhaust.

With 87 octane gas, engine makes constant tatatatata noise at idle (ECU retarding timging?), very audible 'cuz my 12 yr old daughter can hear it loud and clear and asks me what's wrong with the car. LOL

With 89 octane gas, no engine noise but car feels sluggish on acceleration.

With 91 octane gas, car (throttle) feels very light and transmission shifts like butter, very strange though. Can gas can affect shifting?

So I would say gas DOES make a big difference based on my experience!

 

well, the engine is designed to run optimally with the high grade fuel. The lower octane stuff doesn't burn as efficiently under the high compression of this engine. Not sure why it would shift better but maybe the smoother engine operation makes it feel like it does

 

low grade gas on high compressure engine will cause engine knock, which is because the mixed air burns before the spark plugs producing sparks due to high heat form high compression.

 

glad that you learned from experience what we have been trying to convince some people of for years on here.

if it didnt matter, nissan wouldnt say to use premium

 

Premium ALWAYS............

 

"AGREE" some people just don't get it. They think all fuel is the same, but it's not. I used to own a 1991 maxima, went ahead and put 87 octane. At idle made a knocking noise. Switch over to 91 octane, smooth sailing after that. My choice, Shell,76, Mobil,Chevron.........that's it. Premium does a body good!

 

Accidentally the first tank I put in my Maxima (2 years ago) was 87.. I still remember the day I filled her with 93... it makes a world of difference

 

Top Tier rated premium is all I use. 93 octane around here too.

 

Shell is probably the best expirience I've head. I've had a couple bad expiriences with Cumby's, and Mobil is just too expensive.

 

I too played around with this when I first got my max (02 SE) on 87 I got sluggish performance but slightly higher mileage, possibily due to having to drive more conservitively. 89 was an improvement but not enough. 91 (the highest we can get in in comufornia) gives slightly lower mileage but allows the motor to work as it should.

As a side note on low octane fuel, when you use low octane fuel your ECU will retard the timing of your engine therefore opening up your exhaust valves sooner which in turn will cause you to have higher exhaust gas temps. In the short term it's not a problem but in the long term the higher temps can cause your exhaust componets to wear out quicker.