do I need to run an 89 octane gasoline
It can run 89, but you can run the other 2 octane fuels too. If I run premium fuel in my 05 I get about a 2mpg improvement, but for the cost difference I just stick with regular.
no, you do not need to run 89 octane, 87 is perfectly fine for a half ton Silverado.
Try it and see if your power is up or if the mileage goes up. If your truck is pinging on 87 then I would use 89 or premium.
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