does the infiniti m 35 2006 awd only use premium fuel???

The owner's manual tells you to use higher grade gasoline, but the cost per mile is significantly more. You will get better fuel economy with 91 or 93 octane on the highway." When running a higher octane gasoline,what you're really paying for is engine protection. Octane in fuel is something that prevents the fuel from pre-igniting so that the engine runs smoother/more efficiently. In the 4 stroke combustion engine there is the intake , compression, power, and exhaust strokes. During the compression stroke the fuel-air mixture is compressed before a spark plug ignites the mixture to produce the power stroke. If the fuel is of too low an octane rating for the compression in the cylinder, then it may pre-ignite, and cause engine pinging which when constant, can severely damage an engine. This engine is equipped with a knock sensor to detect this phenomenon. When the sensor picks up engine knock/pinging, it retards the timing, which adjusts for pre-ignition. As a result, you get less power from the same fuel. Also stay away from ethanol fuels as much as possible. These fuels have a finite shelf life partially because they absorb moisture. If the ethanol fuel your using has already absorbed moisture you will be running that moisture through your engine causing damage to the entire fuel system. The small cost savings from ethanol will REDUCE MILEAGE and INCREASE REPAIRS.

My manual RECOMMENDS Premium but I run REAL Regular without Ethanol and it runs fine. I get about 24 @ 70mph on the highway and the Regular cost about 15 cents more per gal over PREMIUM but I didn't buy the M35 for economy.