My PSD has the "romps" in real cold startup without plugging in with both oil changes before Amsoil, I used Rotella 15W-40, when I switched to the 5W it spins over a little better IMO, and starts better under the same conditions in the winter.
So when I saw Amsoils 5W-40, I figured I'd just run it year round vs their 15W-40, I agree with Dieselman in what he said about it.
5W-40 will eventually replace 15W someday I guess, 15W just seems too thick for flow in cold engine winter startup, especially when our PSDs need the oil pumping to fire the injectors. All the new diesels are requiring 5W-40, not a whole lot different in how the oil is used besides different mechanical parts and configurations, unless Im missing something.
I also assume 5W-40 is for emission standards, as it was not available until just recently.
Last edited by Lord Tauk : 05-30-2007 at 03:19 PM.