Those of you that have a 6.4 hemi truck are you using Pennzoil 0w-40 oil or have you used other brands of 0w-40 oil? If memory serves me right it says in the manual to use an oil that meets a certain spec and Pennzoil is the only one that has the spec listed on their oil container, but Pennzoil and Chrysler/Fiat or whatever u want to call them are in business together. Didn't know if Valvoline or Mobil 1 0w40 is the same just didn't have their oil tested for that spec?
