This jug was In Stuart, Fl. WM in FL seems to have trouble selling synthetic diesel oils, I bought some mobil 1 TDT 5w-40 cheap and noticed delo 5w-40 & t6 5w-40 heavily discounted. Seems diesel owners are just buying 15w-40 for $11 gallon vs $20 for 5w-40 syn's. Seeing t6 in 15w-40 & this delvac syn 15w-40 shows that they are trying to find a market. Most truck manuals call for 15w-40 above freezing anyway.. I did notice a boat that I work on specifically requires Mobil ESP 5w-40 for the MAN common rail diesels, Im guessing HTHS is excellent with the Mobil esp 5w-40..