Ford is recommending the use of a new Motorcraft diesel engine oil for its Super Duty trucks and warning fleet and commercial customers to avoid using most new CK-4 or FA-4 oils because they may cause damage to the engine, the company told AutomotiveFleet.com.

Motocraft's WSS-M2C171-F1 formulation should be used in all Power Stroke diesels, especially the 6.7L that powers the F-250, F-350, and F-450, because it better protects the engine against high-mileage wear, according to the company. Ford had previously recommended CJ-4 formulations for its Super Duty trucks. On Dec. 1, the American Petroleum Institute began licensing the new CK-4 and FA-4 oils. CJ-4 oils will eventually be phased out.

Commercial users should avoid the FA-4 formulation due to its low viscosity. CK-4 motor oils should be avoided because they provide "inadequate wear protection," according to a statement. The oil drain intervals remain unaffected, said Sherrice Gilsbach, a Ford spokesperson.

The oil certification information is located on the back of the oil pouch in a circle known as the API donut.

Customers shouldn't use oils labeled CK-4/SN unless they have been approved by Ford to meet WSS-M2C171-F1. This is possible with SAE 10W-40, 15W-40, 5W-40 and 0W-40 oils. SAE 10W-30 oils showing CK-4/SN cannot meet WSS-M2C171-F1.

Motorcraft Super Duty diesel motor oil is formulated with premium hydroprocessed base oils and additive technology necessary to meet WSS-M2C171-F1. This new oil also meets the requirements of Cummins CES20086, Detroit Diesel 93K222, Volvo VDS-4.5 and Mack EOS-4.5, according to Ford.

View a video from Ford here: