Fuel Grade 91 vs 93...
 

are they the same?
:support:

no, one's 91 and one's 93

I use 94 which is FAR superior to 93. ;)

Use whatever you think is best....premium fuel is premium fuel... :chuckle:

one is more expensive.

This is true....whatever fits your budget..... :scratch:

If you live near sea level premium can be as high as 94. If you live in Denver premium may be only 89.
I live in the Dallas area (+/-300') and most premium is 93. When I go visit my mother (+/-3,300') the premium is only 91.
As near as I can tell, 90 or 91 @ 300' works just fine. That would be the mid-grade choice here. The regular grade seems to work fine too but I think I have heard some spark knock in high temps with A/C on... so I buy mid or premium. But that's just me.

I go the same way, on sea level out here. They do not offer 93 on base anymore so I use 89 until they have the 93 back. No knocks and power is still OK. It is winter time also so using 89 is no big deal, not going to hurt anything. Hell, even if you put 87 in at a decent gas station, as long as you have no knock, change your oil.......should not be a MAJOR issue. The car will adjust the timing to the octane to prevent knock. Just my experience. Nissan does say Premium....91 is recommended for maximum performance....but not REQUIRED.

I get my gas on the Air Force base, convienent, and cheaper than off base. If they get Premium back, the 93, will run it again, until then, with no knock, car runs fine. I STILL SAY....even 89 is OK with no knock. Now, once you start doing some mods.....that is a different story. :calder:

Yeah, but Canadian octanes aren't worth as much, and when you convert them to U.S. octanes, they're only 91. ;)

Mike

(Bunch o'comedians, aren't we.)

Our Canadian octanes are more stable and far less likely to explode at the slightest provocation as are the American octanes. Thus they are superior. lol

nothing but 93 for my baby. used 89 once heard rediculous knocking and said never again!!

As to the original query, several here explained it well. In my mind, and with my style driving, 91 and 93 octanes are effectively the same. I do understand the reason the fuel companies vary the formulation slightly based on altitude/season.

For me, the primary objective is to avoid any knocking. Any Maxima that knocks with 91 octane fuel is in need of a tuneup, even if it has just been purchased new.

American octanes are sometimes misunderstood by foreign octanes, but they are simply more protective of their engines and react more aggressively to knocks than some foreign ones. If those foreign octanes work for the engines in their respective countries of origin, they certainly should use them. But if they attack an American octane within its own engine, it's likely to make a noise that sounds like "Let's roll!".

;)

Mike