I know it might be a pain, but i would add a second gauge to verify the OEM gauge.
If you had a 6.5 then those temps could be normal...
My Dmax runs cool even in the summer and it has probably had zero maintenance on the cooling stack.Dmax's are not known for overheating, especially not hauling any weight
90 Chev 3500 c/c 4x4,6.2na,400 auto,4:10 gears.DSG Timing gears,main girdle, isspro tach, pyro,boost,oil and trany temp.Dual Tstats, High volume peninsular pump,on shelf, Custom turbo and intercooler 85%complete. Change of plans for the dually, it's going to get a Cummins. Both trucks are Blue 90 4x4 crews