I read Steve Swedbergs Automotive column regarding API CK-4 and FA-4 in the September 2017 edition and wanted to make you aware of some inaccuracies.

Specifically:

The column states that the T-13 test is for wear and corrosion. It is for oxidation.

The column states that all major OEMs are using CJ-4 for factory fill. I am aware of no OEM using CJ-4. It is my understanding that many OEMs are using CK-4 or FA-4 for that purpose.

The column also states that some OEMs have developed their own specifications based on performance concerns with CK-4 and FA-4. In fact, OEMs have historically supported the API standards while also promoting their individual OEM specifications. This was the case with the introduction of CK-4/FA-4 oils as well. Truck & Engine Manufacturers Association members have not expressed concern regarding CK-4 performance in the field.

The significant improvements associated with CK-4 and FA-4 oils, including increased drain intervals, are important. I am glad they were included in the column along with the potential fuel economy improvements. At the same time, I am concerned that the errors listed above will delay, rather than accelerate, industry acceptance of these important new oils.

Roger Gault

Truck & Engine Manufacturers Association

Chicago, Illinois

Editors note: Thank you for bringing these typographic and technical errors to readers attention. Most heavy-duty engine builders are using API CK-4 for factory fill (not CJ-4), and the T-13 test indeed measures oxidation stability at high temperatures.

However much enthusiasm heavy-duty engine manufacturers have for CK-4, Mr. Gault should realize theres a holdout among EMAs 29 members: Ford Motor Co. last year told vehicle operators not to use API CK-4 oils in any of its medium-duty diesels, unless the product passed Fords own specification with additional requirements for wear protection.