what's funny about this thread is that most people giving answers would be asking this question if their vehicle said "premium fuel only"
When a vehicle says premium fuel it DOES mean use high test fuel.
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If the manufacture warns to use "premium fuel" the engine AND the computer has been designed to use premium fuel, that is what it needs.
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It cost between 2-4 bucks xtra to fill the tank with premium, it cost the manufacture much more then that to print that on the dash, in the owners manual, and on the fuel door, it's there for a reason.
remember the old saying, "pay me now or pay me later"?
use premimum or high-test

and don't look back, your engine and wallet will be happy you did.