RF Overlord

This is not your father's Geländewagen. GC is a very thick 30 (almost a 40) and the Duratec 3.0 is spec'd for 5W-20. Don't get me wrong; GC is a great oil, just not for this application. It will run forever on the factory-recommended Motorcraft 5W-20 and that's a lot easier to find than GC, too.