The best oil's are Amsoil ! Had A 1999 24V Turbo diesel for 17 years and it was as strong as ever i put everything on Amsoil . You can go almost 3 times longer than dealer specs and save a fortune on labor and be overkill if you change yearly and get better mileage and spoil your truck at the...
I use Amsoil Injector cleaner and do notice a significant MPG increase filling from the same source .Used all Amsoil in my previous 1999 Ram for 17 years with great results .