The T6 5W30 multi vehicle is rare because only a few newer diesel vehicles, like the Ram 1500 Ecodiesel, were ever specc'ed for it. The VAST majority of diesel operators are using 15W40, with a small minority (including me) using xW30 (10W30 & 15W30). None of which would hurt a non-oil burning, out of warranty gas engine, regardless of the SN rating.