2010 ProStar Cummings engine guzzling 4 bottles of coolant

I have a 2010 ProStar with a Cummings engine that so far just gulped down 4 gallons of coolant. I checked every spot on the engine for leaks, the oil isn't milky, the truck is staying within normal temps. Now I just brought the truck in late augest and the first 2 bottles I put in was to refill the reservoir because it was low. I just added two more bottles and filled the reservoir up to the top. Now that the truck is completely cool the level is now between full hot and cold. I'm going to get the cooling system checked out but what could it be besides an internal leak?

 

It turns out that the leak was coming out around the hose clamps of the turbo booster. The clamps need to be adjusted. Since the TA have a "don't touch the turbobooster" policy I have to go the dealership. Just to get two clamps tightened.

 

There is no white smoke. The time frame to added coolant is 3 days. The EGR cooler is around the turbobooster right?

 

I hope not. Engine temp is staying normal though. How much does the cooler cost?