Kioti is covering my tractor engine so far as warranty. They designed and built the engine and specify 10 W 30 Diesel oil so that is what I use. I have selected Shell Rotella 10 W 30 and have 500 hours on my CK20 (s)and my engine hums along as good or better than the day it was delivered.
I will continue to use their selected lubricants. I will not deviate until I hear Daedong change it's specs but especially while it remains on warranty. The choice is yours. Perhaps the use of 15w40 or a synthetic is just as good but my choice is to wait until I get the go ahead from the company.
I have decided to drain out the Mobile1 and put it in my car. I'm so glad I read this post. This is my first desiel ever owned, and when i read the manual, my eyes skipped over the part that says CC CD oil.