I am now running slightly higher engine temperatures on my 2005 Cummins. The owners manual indicate running below the 95C temp mark at center dial as normal. Last year I could run up a large grade pulling max traler weight with the A/C on without going over 95C on the guage. Now it will run there at hiway speeds all the time. Rad interior fins are clear, coolant is clear, thermostat has been changed (no temp. change resulted), cannot see any pluggage in the cooling fins on the rad. I have 120,000 K.M. on the truck and change oil, oil filter, fuel filter sooner than reccomended. There are no error codes showing up. Has anyone any light to shed on this as I have had it to the shop twice and they don't see anything wrong.