I know that I've heard that the minimum is the new coolant level. ive had this truck for 8 months.. I started to notice that the coolant level was getting lower and lower and would stay around the minimum level, well after the EGR delete i Noticed that the coolant in the reservoir was empty when driving it for an hour or so.. i have added coolant to it and continued on and just figured that the guys who put the EGR delete on didnt properly fill the system, but the last time i traveled i stopped to check oil and coolant level, and the reservoir was empty and the reservoir was under pressure, i slowly released the cap turn by turn and the coolant started to fill the bottle again. so i slowly tightened it back and held the pressure so the coolant wouldnt splach out, and the coolant would receed back down out of the reservoir. finally the pressure wasnt too bad so i opened it completely and the fluid came back just below the low line and it took 2 gallons of water... ????? my truck doesnt ever get hot... Gaskets???

 

Probably the little hose that hooks from oil cooler to EGR cooler delete, if it is using the factory hose they are known to leak on occasion.

 

Well you can't check the coolant level with it hot and running, it pulls the coolant out of the bottle and uses it in the cooling system. You need to check it with no pressure when the motor is cold. Fill to the MIN line and leave it there. Check it again after a week or so. See if it's gone down. That bottle is just an "overflow."