What are you using ?

When i had my 340 built by a guy that builds pulling motors i asked if i could use shell rotella 15/40 as my oil. He stated that i could not only use it as a break in oil but continue to use it as a everyday oil . It has zinc and all the other things that a motor needs . I know after 43 years of trucking all the big truck engine builders use it and they all can't be that wrong. Just my opinion that's my oil and i'm sticking with it.