Basta huwag lalampas ng 50% coolant kasi masyado nang matapang yun. As much as possible. Kalahati lang ng dapat ng amount ng tubig ang coolant or even less pa (~40%).

Kapag walang coolant, kakalawangin ang internals ng cooling system. Coolant is not only a coolant. It is also a lubricant and anti-corrosive agent.

Dapat once a year (or even less) ka lang mag lagay/palit ng coolant. If you keep losing coolant. May problema ang sasakyan mo.