So my Add coolant light came on today. I had a slow coolant leak mainly in the winter with the N/A engine. however i have a JDM engine in there now. and i used the heater last night. but didn't smell coolant. i am not sure where the coolant is going. it is the same rad i had before

 

did you check your overflow tank?

 

bone dry.

 

Go to an auto parts store and rent a coolant pressure tester, it should make the leak obvious.