I respectfully disagree on it being a waste of money.
My wife has a 2011 Denali with the 6.2. It really is a great set-up. I can only imagine it is even better in 2016. I thought here owners manual said to run premium fuel. Maybe she is waster her money since I did not confirm what the manual says about fuel, but I can't say we're experience any of the negatives listed above.
This could get into a log debate, but on the dyno you can absolutely push the limits of timing with higher octane. If you actually look at the timing maps programmed into the PCM, they vary for tow mode and regular, and have a range of retard once the knock threshold is crossed. Better fuel will let you stay in the more powerful part of the timing map when pushing the engine.
Granted, light load, modest throttle and the higher octane will not be nessisary on many engines. My experience towing with the Chevy V8 is the better octane is worth it.
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Paul III
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