PISTON RINGS WITH MULTI-LAYER HARD FACINGS COMPOSED OF AN OUTER BREAK-IN LAYER OF REFRACTORY POROUS SCUFF RESISTING MATERIAL, SUCH AS MOLBYBDENUM, OVER AND BONDED TO A MORE REFRACTORY, LESS POROUS MATERIAL SUCH AS A TUNGSTEN CARBIDE ALLOY WHICH, IN TURN, IS BONDED TO A BASE RING BODY MATERIAL SUCH AS IRON. THE OUTER LAYER, ALTHOUGH REFRACTORY, FUNCTIONS DURING THE ENGINE RUN-IN PERIOD BETTER THAN THE UNDERLYING MATERIAL BECAUSE IT IS SOFTER AND MORE POROUS, AND AS IT WEARS AWAY AND OXIDIZES, A MORE REFRACTORY LESS POROUS UNDERLYING LAYER COMES INTO OPERATION TO INSURE LONG LASTING HIGHLY EFFICIENT SEALING OF THE COMPATABLE RING AND CYLINDER SURFACES FORMED DURING THE BREAK-IN OPERATION OF THE ENGINES.