I am going to hate this but I have tried searching and I am more confused now that when I started.<br/><br/>I need to <strong>add</strong> some oil to my 97' 8.3 engine, is the Delo 15-40 still the correct oil?<br/><br/>I see from the PO that he used Delco 15-40 in his first oil change but all the others he just says oil and filter change.<br/><br/>I know the makeup of diesel has changed since 1997 with the sulfur...