2003 Chevy Silverado Gas Octane

First of all thank you so much for your donation. You should always use the grade gas that your owner's manual say's to use. As far as you doing any engine damage from using the 89 octane without tearing the engine apart or maybe using a bore scope you really can't tell. But if you haven't heard any pinging or knocking in the engine then I would say you probably haven't done any damage. The higher the octane the slower the gas burn's so the higher the compression ratio of the engine the higher the octane gas that is needed. If it say's 87 octane in your owners manual then use 87 octane save your self some money. It won't hurt your engine to switch to the 87 octane now.

Thanks again for the donation and thank you for using 2carpros.