Let me repeat. 30-40k oil drain intervals. 600 to 900k on the motors. Nothing more than a couple of injectors between the three 900k plus motors. All on LE or Amsoil.
The good oils do not foam when they get old. The only thing you need to be aware of is depleting additives. Without the add package, your oil will not preform as well. No snake oil or mystery to it. The more specific elements in an oil the better it protects. It also cost more to put those additives in it. Phosphorus is one, Mobile puts one third the phosphorus that we do n our oil, that makes the oil more robust but more expensive. Base oils are also important. Chevron, Shell, Valvoline, Mobil are first and foremost fuel manufactures. Their lubricant base oil is what is left over from the lucrative fuel business. Amsoil, Lubrication Engineers and the like can pick where their base oils come from. HUGE difference in performance when all the variables are accounted for. It all comes down to chemistry and tribology.
