Thanks guys and gals out here on 4x4wire.com I tried that oil change to the Mobil1 Syn 0w30 and damned if it didn't all but get rid of that signature Rodeo engine noise. Granted it still makes a slight tick at startup, but after a couple of minutes, I couldn't even recognize my engine sound. Has anyone had long term experience with using this oil in our rigs? Does the benefit only get better with continued use? I've been using synthetic for a while now, but have occasionally thrown in a bottle of Syntec or Rislone. Does anyone know if I should still use Syntec or other additive from time to time for my high mileage engine?