V, Na & Ca (Calcium generally from the lubricant additives) salts burn to ash during combustion. Upon resolidifying with cooling, they form solid, brittle amorphic layers on hot engine components such as exhaust valve seats, heat exchanger pipes and turbo charger blades. These layers break off during mechanical stress, forming channels through which hot exhaust gases pass and burn off seat material.
- To reduce this problem operate valve seats below 400°C or buy selectively low V content fuels. RMA25 is designed specifically for this purpose but is not available everywhere.