[TAKPAK]

Chevron Delo 400, 15/40. Have used it for almost 30 years. I have had no problems with any of my vehicles, gas or diesel. The dealer I have my truck serviced at uses the Chevron products there. That said, I would not hesitate to use any of the name brand big rig oils that are available, be it Delvac, Rotella, Royal Purple, etc. I would be hesitant to use some off brand oil though, you don't know what additives (if any) are in it.