Hi I'm new to the forum and I just wanted to share my experience running Pennzoil platinum and Pennzoil ultra in my personal vehicles. I've run Moble 1 synthetic for many years and always felt confident doing so. I kept hearing people rave about pennzoil so I figured I would try it out! At first my 3.5 ecoboost explorer sounded great, very quiet! My cammed and supercharged gmc sierra sounded the same but once I hit around 3,000 miles in the explorer started the dreaded cam phaser rattle! I decided to change it immediately and I used ultra platinum this time and 2,000 miles later same thing but worse! Again I changed it immediately back to mobile 1 and made it to my 5,000 mile interval with zero noise! Also my GMC is sounding noisy with around 2,000 miles on the pup as well but maybe now I'm paranoid! Has anyone else experienced this?