My co-worker who builds engines recently asked me to comment on the removal of zinc and phosphate from diesel oil. My response was "Huh?" As a builder of race engines, he is keenly aware of oil properties and what causes wear and what doesn't. He told me that API specification CJ4/SM for diesels is going to cause more wear than CI4/SM. The Motorcraft oil I use, as well as the tried and trusted Rotella-T has moved to CJ4. This is because of the catalytic converters in all the newer trucks. Our older rigs need their zinc and phosphates! He turned me on to this stuff which I was pleased to read is locally grown for us Quakers. It's being marketed BECAUSE it is CI4, as a specialty oil. I'm afraid it may be time for me to abandon the Motorcraft Oil I have been using for a quarter century.