I'm sure this has been a topic over and over again, so bear with me.
My revious truck... 2000 1500 with the 5.2 Magnum V8. Ran 89 octane gas. I felt like it was better for the engine.
New one... 5.7 Hemi. Manual says 89, but I've heard some things. I've heard that running 91 octane will...