So...3750 miles on the oil...how many on the truck? Is that 3750 too?
You should go online and change your units (miles instead of hours, qts instead of gallons etc) and fill in the rest of your info (sump size etc). Polaris uses this info to help them decide if things are AOK or serious enough to warrant calling you about impending doom.
HDEO in Diesel Engines. No spark plugs here.