Mercury - Quickare Fuel Treatment Additive Fuel Care System Liquid Formula 8M0058690. Overview. Every boater knows the uneasy feeling of turning the key after your boat has been sitting for a few weeks. You hope the engine wakes up cleanly, without stumbling or coughing through stale fuel. That peace of mind - the kind that makes you relax the moment the motor fires - comes from taking care of your fuel system long before you hit the water. Mercury Quickare Fuel Treatment Additive gives you that