oil grades

I have my dealer do it. I use the Motorcraft 5W-40 synthetic.

Been using 15W-40 Rotella since new (2006)

Full Timed for first 7 yrs towing 14K 5th wheel weekly.

I am anal about oil changes.
Change oil/oil filter every 5000 miles.......fuel filter every 10K and air filter when 'dirty'

The Shell 5-40W synthetic - it's cold here in the winter, but I run it year round

Bill

Rotella 5w-40 since day one

Rotella T6 5W40 for 110k miles.

Make sure that your 15W40 Rotella is low SAPs (Made for trucks with DPFs), or you could have DPF issues.

taviking22 wrote:
Rotella 5w-40 since day one

Ditto. Synthetic is mandatory due to the winter temps we get where I live, but I'd probably run it regardless.

I have always used Rotella T 15W40 in my 7.3 and still do. But I use Rotella T6 5W40 syn in the 6.7.

5W-40 syn is the Ford approved heavy duty oil. Heavy duty has a bunch of triggers including towing more than 1000 miles (but they don't say if that is per oil change) or idling more than 10 minutes per hour (which isn't much if you do any city driving). I do both so it is 5W-40 for me in our 2012 6.7. 15W-40 is only good down to 20 degrees F which is not a problem in the south but the full synthetic oil will give better protection in very high temperatures of the south.

I only use 15w-40 dinosaur Diesel oil. Not too particular about brand. I'm not convinced that syn is all that it's cracked up to be. Plus I change the oil every 5k.