The present invention relates to an apparatus and method for delivering tungsten from a to a fuel combustion system or to the exhaust therefrom. By the present invention, tungsten from the lubricant or the fuel will interact with iron from the combustion process. In this manner, the tungsten scavenges or inactivates iron that can otherwise poison catalytic converters, sensors and/or automotive on-board diagnostic devices and/or reduce the operation of spark plugs. The present invention can also lead to improved durability of exhaust after treatment systems. Supplying tungsten acts to change the characteristics of iron deposits formed by combusting a fuel with iron.