I had service done on my 6v92 last year at Stewart & Stevenson in Denver. For oil they used 15w40 which I now know is a no no for this motor. To remediate this I've been on a search for the recommended Delo 100 40wt. <br/><br/>Started at NAPA. None in stock but they can order it. A week later I go in to pick it up. It's not Delo 100 but Delo 400. They can't get Delo 100. Next I...