Ford WSS Engine-Oil Specifications Explained: 945-B1, 961-A1, 962-A1 and 971-A1
Ford’s WSS-M2C engine-oil codes are vehicle material specifications, not interchangeable shorthand for viscosity. This guide explains how to read common 5W-20, 0W-20 and 5W-30 Ford WSS requirements, why API or ILSAC marks still matter, and how to choose oil without assuming that a newer-looking code fits every Ford or Lincoln engine.