The coolant system consists of your radiator, hoses, valves, coolant reservoir, and coolant filter and of course coolant. To keep the cooling system properly maintained you have to keep a close eye on the coolant reservoir/tank. If you see that the level is below the max line then that means you have a leak somewhere, the leak if not corrected will eventually drain the tank and once you pass a certain threshold you will notice the engine temperature gauge climbing into the red zone which means you got trouble. If you let this go on to long you can warp the cylinder head and then you’ll have a very expensive head gasket to replace! Always keep an eye on the coolant level! Replacing the coolant and filter at the suggested intervals will also keep your hoses and radiator in good condition.