While they do recommend premium(93) gas for the 6.2 it is not required. As low as 87 can be used as long as their is no knocking.
In our '11 Escalade we never used premium and had around 120k on it when we traded it in and never had a single issue with the engine. We averaged around 17mpg.
We've been using regular in our '21 Denali so far and only averaging 12.5mpg after 1400 miles. Told the wife the other day next time to go premium for the next 1400 miles and see how it goes.
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