Originally Posted by LubricatusObsess
Ford recently published an oil chart for 2020. Up to a week or so a go, they still had the 2019 chart posted. I didn't look for differences between the two. I think this new chart is much more difficult to read. I posted the 2019 chart in other thread(s).
Note (4) is for the 6.7L Diesel.
Note (6) continues Ford's worry about insufficient antiwear capability of API CK-4 oils. Shell Rotella T6 5W-40 meets the Ford Spec and is on the approved list.
Note [4]: Check Owner's Guide for appropriate viscosity depending on ambient temperature, duty cycle and biofuel content.
Above 20°F(-7°C) use SAE 15W-40 WSS-M2C171-F1 (except 3.2L Power Stroke® Diesel)
Above -20°F (-29°C) use SAE 5W-40 or 0W40 WSS-M2C171-F1, CJ-4, CI-4 [6]
Above -40°F (-40°C) use SAE 0W-30 or 0W-40 WSS-M2C171-F1, CJ-4, CI-4 [6]
Note [6]: Oils showing CK-4 and CJ-4 in the API Donut are not recommended unless they are approved to WSS-M2C171-F1
http://www.fcsdchemicalsandlubricants.com/quickref/oilchartUS.pdf
The above information doesn't coincide with owners manual information as the 6.7 in normal service specs 10w-30.
My current 6.7 has seen nothing but 10w-30 since new and currently at 125,500 mi. The engine oil is liquid cooled and oil temp is readily viewable through the dash info screen. As long as oil temps aren't constantly approaching defuel temp, which is 248f, there is absolutely nothing wrong with following owners manual recommendation of 10w-30.
My 6.7 is a work truck, constantly loaded, running in 90+f temps through the summer at highway speeds. UOA data has always stated continue what you're doing everything looks great, and I'm going until the IOLM states to change oil now, which is usually 10,000 mi. Plus or minus 500 mi.