You should prepare your vehicle to drive reliably, and not need anyone on call.
Do not fill your radiator with water. Radiators are part of the cooling system and the cooling system is destroyed slowly if you use plain, tap, sweet, sour, hard, soft, mineral, battery, or any other kind of water in your car. The car will leave you stranded on the side of the road at least once, guaranteed, and the repairs are often costly and repetitive because these idiot mechanics rely on your cooling system failing piece by piece to make their meagre wages and secure a steady, consistent monthly clientele. It's all they know.
Clean and rust-free internal engine cooling passages and a good quality radiator, hoses, clamps, radiator cap, water pump, thermostat, good quality coolant (which contains water, but also a lot of other things that help protect the system) will make it basically hands-off save for occasional maintenance. It will contribute significantly to making your car be on the road more, rather than being parked at a mechanic's shop or on the side of the road.
