The hard way! Had to add about an inch of coolant a few days ago to bring level up in reservoir. No drips no smells no nothing until yesterday when about a block from home steam came rolling out. Turned out to be the coolant line from the reservoir just broke off sending the sticky stuff all over my engine compartment. Called a local dealer and they said from the description of what happened..plastic connection broke inside the coolant tube, all but the hose itself and maybe some lost coolant would be covered under the 5 year engine warranty, even towing. Hope it goes as they said and feel lucky I still a a few months on the engine warranty.