Join Date: Mar 2019
Location: Calgary, Alberta
I would do it after about 2000-3000 miles. You can use both the ford 5W30 FA-4 oil (WSS-M2C214-B1) , or a CK-4 5W40 (WSS-M2C171-F1). The FA-4 has a much lower HTHS viscosity which makes it easier to pump and thus yields better fuel economy. A CK-4 (i.e. rotella) is a heavy duty oil which ford recommends for "severe duty" service (towing, idling, stop and go, extreme temps, hilly terrain, and bio-diesel use). The CK-4 has a higher HTHS viscosity, so it will take more energy to pump, but it will yield a thicker film strength over components. Now the engine has been designed for FA-4 (new bearings, etc), so it's totally fine to use, however i'm more inclined to use the CK-4 oil as I plan on keeping the truck for a long time, and thus happy to sacrifice a 0.5 MPG fuel increase in the name of engine longevity. I may switch back at some point once we know there are no long term issues with FA-4. Ram had issues with 5W30 and switched to rotella 5W40 a couple years in, this FA-4 oil is even thinner at temp than the 5W30 ram started with. If you're in-between, Amsoil has a 5W30 CK-4 option that seems like a good middle ground. I'm in Canada and run Klondike 5W40.