Well i Don't have much experience with Hondas so don't know much about them and the type coolants recommended by honda in them....
Don't mix two different coolants together....!
But for aluminium engine blocks the coolants are different and for iron engine blocks coolants are different the coolant by ZIC is safe for use in aluminum engine block's...
About coolant decreasing mechanics are wrong it doesn't matter how old is the car the coolant should not decrease there might be some tiny leak in your car's cooling system which you are unable to find might be leaking hoses, joints, radiator, headgaskit, etc.....
Sent from my D2502 using PW Forums mobile app