it's better to use UV color coolant like UV green or just normal red color coolant.

so when you park at clean floor like shopping mall parking.

if any leak you can notice.

i kena before, park my car at pavillion, come back the whole engine bay floor area full of "RED" water.

so i know it's water coolant water leak liao.

in my case is bottom radiator hose crack, cause the leak.

you might want to look into top and bottom hose.

check also your radiator top cover see if any crack ( not radiator cap )

other than that look at your water pump area ( near timing belt and pully area ) to see any noticeable water mark stain like UV green stain or red color stain.