What type of coolant do I use for the 2004 ford explorer?

If Your 2004 Ford Explorer needs more coolant I would recommend using green coolant for American vehicles in it. That is what comes stock in the car and can be used to top off the system. If You have had Your coolant flushed by a third party mechanic then You will need to check with them to see what coolant You have. Never mix different types of coolant because it can reduce the cooling capacity, and rust the components in Your system. If You are unsure and Your existing coolant is not green then I recommend adding distilled water. Your coolant may boil slightly easier but it can be used to top it off without damaging anything until You confirm the coolant You have.