Looking at the specs for the 6.7, it says 10w30 for normal use. Also see that 5w40 synthetic can be used in severe duty apps. Has anyone switched over to 5w40 for normal use? Does it hurt to do so? I cannot see where it do any harm, but see where it would do more good (better oil flow in cold weather, better protection when hot and less prone to breakdown).Plus can one still go by "old school" method of changing oil every 5k VS waiting for light on dash telling you to?In case your wondering, we bought a 2015 F350 CC w/ the 6.7. Was kinda bittersweet seeing our old '03 go, but it was time.

I use 15W40 and the truck tells me when it needs changing. I personally believe that some spend to much time and money worrying to much about nothing.

oil is oil and make sure you buy CJ4 10w-30 not regular 10w-30.

I just use the 10W30, and let the truck tell me when it wants new oil. The truck's sensors and computers calculate the oil change interval based upon temperature, viscosity and load.

If you operate your truck at max power for extended time in hot weather a second number 40 weight offers more protection vs 30 weight. Flowability to provide lubrication on cold start ups is said to be more of a concern in light duty vehicles. We often "enjoy" both conditions so we use 5w40 synthetic diesel oil. If you have winter where you live:Cold lube oil flowability

From the manual:5W-40 or 15W-40 oil is recommended for fuels with greater than 5%biodiesel (B5).Since I never know what is in the fuel, I use 5W-40 synthetic. I also use the OLM.

Oil vesocity for 6.7 powerstroke | Good Sam Community

Fulltimer50
Explorer
Dec 06, 2014
I use 15W40 and the truck tells me when it needs changing. I personally believe that some spend to much time and money worrying to much about nothing.
gmcsmoke
Explorer
Dec 06, 2014
oil is oil and make sure you buy CJ4 10w-30 not regular 10w-30.
TucsonJim
Explorer II
Dec 06, 2014
I just use the 10W30, and let the truck tell me when it wants new oil. The truck's sensors and computers calculate the oil change interval based upon temperature, viscosity and load.
noteven
Explorer III
Dec 06, 2014
If you operate your truck at max power for extended time in hot weather a second number 40 weight offers more protection vs 30 weight.

Flowability to provide lubrication on cold start ups is said to be more of a concern in light duty vehicles.

We often "enjoy" both conditions so we use 5w40 synthetic diesel oil.

If you have winter where you live:

Cold lube oil flowability
Lynnmor
Explorer
Dec 06, 2014
From the manual:

5W-40 or 15W-40 oil is recommended for fuels with greater than 5%
biodiesel (B5).

Since I never know what is in the fuel, I use 5W-40 synthetic. I also use the OLM.
Trackrig
Explorer II
Dec 06, 2014
I run Mobile 1 5W40 synthetic in my Ford diesel because I like synthetic and our temperature swings. I've run it over 15,000 miles before and oil tests from Cat came back telling me I could run it longer though I do stay with changing it every Spring when the weather turns nice.

Bill
The_Texan
Explorer
Dec 06, 2014
Do you know what the difference is between "normal" use and "severe" use? According to the manufacturers definitions, there are very FEW people I know that the manufacturer would classify as using their truck under "normal" conditions. Go with the 5-40 and let the truck tell you when to change.
FishOnOne
Nomad
Dec 06, 2014
I use Shell Rotella 5W40 year round.
Travlingman
Explorer II
Dec 06, 2014
FishOnOne wrote:
I use Shell Rotella 5W40 year round.

X2
C-Bears
Explorer
Dec 06, 2014
CJ-4, 5-W-40 for me. Since about 80% of my miles are towing I go by severe duty maintenance schedule. Only waited for oil change notification light to come on once before I changed. Probably waste a little bit of money but I change a little earlier than required.