ground hog man, I was thinking along the same lines as you with the 5-40 rotella, I can buy it for the same price as kubota oil. What temperature range to you encounter where you live? Also is there any truth to not being able to go back to regular oil once you use synthetic? I need something which will handle short periods of -10 degrees or so. I,m also considering an oil pan heater. JDH1</P>