For those that have the 6.7 Diesel, what brand and viscosity are you running? Thanks in advance

Ran Rotella T 15w-40 when I had my F250. 5 years, 90k miles and ran fine, only changed it when the computer said to which was about every 7500 miles.


Edited to 15w-40 not 10w-40

Mobil Delvac XTreme 15/40. It�s a Synthetic Blend and has treated our fleet very well.

I have Ford change my oil, surely they engineered their oil for their motors. But maybe not, who knows.

Ford and every other manufacturer don't engineer oil. They contract oil manufacturers to package what grade and API spec they want. For the 6.7 Ford recommends 5 different grades as acceptable depending on temperature range. Any API rated CJ-4 in grades 15W-40, 10W-30, 5W-40, 0W-40 and 0W-30 are acceptable.

Well there you go, I use what ford recommends.

Go to Walmart and buy the ford motorcraft diesel oil its fords "recommended" oil if you will and if you have a problem it wont be because of the oil. I find the motorcraft is usually cheaper than the other major oil brands.

I will go ahead and put this out there merely for thought. Today's classification of oil for that engine id CK-4 and FA-4. They were designed to run with lower viscosity to improve fuel mileage. The CK-4 oil is a replacement for the CJ-4 oil that we are used to, and is compatible with the CJ-4. The FA-4 is the "new technology" that will run the lower viscosity and improve fuel mileage, and is not backwards compatible with the other oils. When we got our first 2017 6.7 F-350, there was this classification of oil, and very limited supplies of it. We investigated it, and still use the 15/40 Mobil xtreme in these newer engines. As far as how well it will work in them, I have over 30 units with 180k miles and a handful over 270k miles that have been flawless. I'm not trying to give advice and swing it for one oil or the other, but this is some real world info that may or may not be useful to someone. Also, the Motorcraft Oil is good, I know several individuals that use it, and have had great luck with it.

10w30 Synthetic Blend is the preferred oil for everyday driving and weekend or occasional towing.

5w40 Synthetic is the preferred oil for heavy duty use or towing everyday.

I use Rotella in all the trucks that I repair or that come through my private shop.

Use Motorcraft filters for everything, especially fuel filters.

I have seen what cheap oil and running the wrong oil in these engines do and its extremely costly and some customers have had to re finance there trucks just to afford the repair.

Currently have 1 customer who has got 547,000 miles on his 6.7 hot shot running 5w40 all original engine.

Have used both Rotella (7.3) and the Motorcraft (6.0 / 6.7) but I make sure mine is clean and change every 5000k. That may be excessive to some, but I do it myself and these engines can cost too much to try and stretch oil life. I don't buy into the 7500 / 10,000 oil change intervals. I don' need to risk it.

Plus 1 on the Ford / Motorcraft filters (oil / fuel). Shop around and you'll find you can get the Motorcraft just as cheap as some of the knockoffs.

I would encourage your to take a sample of your oil and have it analyzed for wear, you can get a sample kit at napa for $20 or so bucks. I was just like you up till pretty recently. Modern oil, modern filters, modern vehicles have come a long way. Your probably doing more harm draining it every 5000 and starting it till it builds pressure than running it to 10k would do.

On my wifes car I started at 5000 like you the first 90,000 miles the oil would come out a brownish color, not even black, last 2 changes I have done 7500 like book says. My current diesel does have the egr turned off, but even at 10,000 miles on the oil it isn't ink black yet and oil analysis says it good to go quite a bit longer.

True points... we did have the analysis done on two of the motors and saw more blow by than desired which was contaminating the oil.

And the semi synthetic add's some as well. On long pulls where I'm making a lot of heat in the turbo I tend to be more conservative. Dry startup is a point, but I try to prime / fill everything before startup to minimize the air left in the cavity of the filter. Starting it back up right after means I should still have a good coating on the bearing surfaces.


I have oil accumulators on my other engines so I can prime / charge with oil pressure before cranking.

Have your used oil checked out , Blackstone

Mobil Delvac 1300 Super

15w 40. I run it in a Duramax but it's all the same [censored].

Get better MPGs with 10-30 Motorcraft diesel Oil from walmart on my 2015 F250.