Fuel Info - 87 Octane Is Good At Sea Level
Hello and welcome. You might want to do a search here and also over at titantalk with the simple word "octane." There is a ton of data. There is clear consensus that 87 octane works just fine in our engines at sea level and when not towing a load. It probably will work fine at all but the highest altitudes. People towing, especially in the mountains are getting better performance running 89, 91 or 93 octane.
Our trucks have a "smart" ECU that has the capability of advancing or retarding timing based on octane content and engine load. Over at titantalk, some of the regulars there are really, really deep into engine tuning, engine management systems and all that. They have done a lot of testing and reported the results. It seems generally agreed that running premium fuel is not necessary unless you are at high altitude or pulling a heavy load.
The other possible use is on the drag strip or during performance testing. As best as we can tell the only difference between the engine output ratings on the Armada and the QX56, which has 10 more bhp, is the use of premium fuel in that vehicle. The engine and ECU are identical. Premium fuel in the Infiniti merely allows more timing advance. You can do the same thing by running premium.
To take advantage of the small increase in power (and big increase in cost), you have to let the ECU "learn" that it has higher octane fuel. That requires a little time, at least several pedal-to-the-floor runs where the ECU will be called upon to advance the timing beyond what it has been doing. It may take several days or a good part of a tank of gas.
And there are many who say (I'm one of them) that the increase in power from use of premium is only available under WOT (wide open throttle) conditions, unless you are at high altitude or pulling a heavy load. For most of us, that means you will get no real benefit from the extra cost.
My personal habit is to run regular most of the time. I do tow from time-to-time, and when I know I am going to tow, I'll try to plan ahead and switch to premium (or add as much to the tank as possible) a couple days ahead.
Do the search and reach your own conclusion. There are differing points of view. I offer mine here.