Can you use reg gas in a 2005 Escalade
Yes but just make sure it is top tier fuel, the computer will adjust the engine to make up for the loss in octane rating, you may also notice a drop in fuel mileage, if you don't like the way it performs dumb in some Octane 104 fuel additive, that will straighten it out.
Most every GM car is designed to run on regular fuel. A few of them will run better on Mid-Grade. However, even if the manual says Premium fuel only, it is unlikely that you will notice much of a difference at Mid-Grade. Except that it costs quite a bit less. As "tennisshoes" has noted, stick with Tier 1 fuels whenever possible. The higher level of additives does make a difference.
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