Bought a case to change out my M1 and just wanted to get some opinions on this oil. As far as I know, its the same as the Conco Phillips Motorcraft right? Is this a group II+ / III blend? Its going on an 04 GMC 4x4 that has recently seen some heavy plowing. The M1 has only 3K miles but a lot of idle time/ heavy pushing / high load and RPM etc.