Depends on how you use your tractor. Heavy duty off highway CK-4 oil is now the proper oil for off highway. FA-4 is for on-highway trucks. As always there is a spec that is minimum requirement. Beyond that you would need to have access to serious testing to determine how much the oil exceeds the standard. As for manufacturers oil, remember it is in their interest to get you through the warranty period before it explodes so they are not always the best but they will always exceed minimum spec. Deere, CNH, and Cat are really into marketing their oils. Kubota not so much except for Super UDT2, but even Super UDT2 and UDT are not acceptable in the M7 tractors. When I got my M7 I started replacing oil using Super UDT2 used in my other Kubotas. It even says on line to use UDT; however, the book says to use only UDT-HD. I had my dealer confirm - Kubota's response is to drain the mixture of Super UDT2 and factory fill UDT-HD and replace with UDT-HD.