beginningjockey

Yes the 7.3LPS diesels use a HEUI system. If all the glowplugs and the controller are working good, I would have half the notion you either have the wrong viscosity of oil for winter, or you are using cheap oil in a engine that needs quality oil. All diesels have the same problem of hard starting with the wrong oil viscosity, but not always as pronounced if they do not have a HEUI injection system (some no HEUI Bosch injection pump users, not in trucks AFAIK, but still a diesel, share the injection pump lubrication sump with the engine, and will have the same problem as definite as a HEUI system). Always use CD grade or better oil, Rotella T works awesome in most diesel engines, and it isn't terribly expensive either.Most PS users I have talked to consent without hesitation that Rotella T 15W40 is the best for performance and good starting. In my experience with diesels it has proved to be true (not having a PS I cannot speak directly from my experience, only others).Edit: If you live in mostly cold weather, use 5W40 Rotella T instead of 15W40.