The truck has 139k miles I found reservoir empty and added almost 2 gallons of coolant to get to the fill line. Ran truck it maintained normal temperature and I found no leaks. Has anyone else had this issue?

 

How often do you open the hood and check the level?

 

This ^^. When's the last time you checked the coolant level?

 

Update i placed some cardboard under truck and did see a few drops of coolant seem to drip after truck was shut off

 

Keep an eye on it.