Motorcraft 10W30, 5W40, Rotella or Mobil 1 for 6.7

Doesn’t anybody read the book?

Regarding the recommended oil, your ‘15 model is identical to my ‘16, and per the guidelines in the Diesel engine supplement you should be following the “Severe Service” oil recommendations. Hauling a TC or towing a trailer can have your GVW maxed out, and the terrain you’re traveling, ambient temps, and bio-diesel usage all have an effect on oil life, and the type of oil you should be using. The recommended oil for severe service is 5W-40 CJ-4, which is only available as full synthetic. It even says this on the oil filler cap.





When I was taking my truck to the dealership to take advantage of the “free” oil changes they offered when I bought my truck, they always wanted to put 10W-30 non-synthetic oil in it. After the second time of arguing with them, and making them drain out the non-synthetic, I went back to changing my own oil. Free isn’t free if they’re doing it wrong.

Also, this was the first vehicle I’ve owned that had an oil-life minder to tell you when to change the oil, and I was curious as to how accurate it was. My concern was that it was telling me to change the oil too late, rather than too soon, so I sent a sample in the last time I changed the oil. I’m not interested in getting every last mile out of the oil.

On the last oil change, my oil minder had gone from “change oil soon” to “change oil now”, and I had driven a couple hundred miles beyond that. The report came back saying it was still useable, and the only concern was that there were some oil additive components present that should not have been in the “synthetic” oil I had identified on the submission form. Those components were apparently from the ~1 qt. of non-synthetic oil that was left in the filter from the last “free” oil change.

So like I said, I change my own oil now, and I trust the oil life minder.

:):)

The factory fill is the 10-30 semi synthetic. That’s what my dealer puts in unless requested for the 5-40 full synthetic.

I think it very unlikely a Ford dealer is offering to install the wrong oil in a PowerStroke. More likely something has been misunderstood or lost in translation.

I'd do like I always do on all my vehicles. I use exactly what the manual calls for. I do not deviate. Why in the world does everybody think they are smarter than the engineers who designed the engine?
I'm a fan of Rotella. I've been using it form many years and have had no engine problems in any of my trucks. My current Duramax is at over 260,000 miles on Rotella and the engine runs great.

FishOnOne wrote:
As for the Mobil One vs the Rotella T6 I would go with the T6 since it's on Fords approved oil list.

As for my truck I run Motorcraft 10W30 year round and purchase it and the oil filter from Wal Mart.

Ditto! Much better price at Wally's.

"Book calls for 5W40 (full synthetic)...Local Ford dealer uses 10W30 as standard oil change oil."

Interesting a Ford dealer has decided that Ford doesn't know what is best for its engines.

My Cummins and my Ford have integral oil coolers so I imagine when the engine is at operating temp the oil is running at or near the same temp whether winter or summer. I use the mfg recommended oil spec for proper lubrication on start up.

As for the Mobil One vs the Rotella T6 I would go with the T6 since it's on Fords approved oil list.

As for my truck I run Motorcraft 10W30 year round and purchase it and the oil filter from Wal Mart.

There are extenuating factors with todays engines that nobody thought of before. You can use a wrong oil for some time before issues arise but eventually, they will bite you. Hard.
No way would I use anything but what Ford recommends.

I would go with the 5W40. The early 6.7L Powerstrokes had very tight bearing clearances(3/4 the size of a human hair) and were known to spin bearings in colder climates using heavier oils like 15w40 or 10w30. Also, due to oil routing design, it takes a lot longer for the thicker cold temp oils grades to get to many upper parts of the engine.