Originally Posted By: rw19
What do you guys think about mixing pennzoil ultra with 0w 20 AFE mobil 1
They're both good oils. I wouldn't mix them, though. Mixing weakens the beneficial properties of the two different additive packages.
But yes, you can physically mix API-approved oils because the specifications require them to be miscible with each other. But that only assures they won't separate phases in your oil pan.