P19. What spark plug must be used in a CNG conversion?

The CNG has as characteristic to be a fuel of "very poor" mixture; with this has a bigger difficulty of spark-out, requiring bigger tensions of the ignition system (increase in the order of 5kV). Therefore we must use spark plugs of better of ignition, as the spark plugs Green Plug and platinum. As in the CNG we have greaters required tensions, we must substitute the sparkling plugs with the half of the kilometrage recommended for the manufacturer. Since that the engine and the system of ignition and feeding are functioning correctly.