I would not use anything except for good old #2 diesel. If you are looking for lubricity, use a bottle of two cycle engine oil. Do not put ATF or Marvel Mystery Oil in a modern diesel engine with a high pressure fuel system. The older low pressure systems liked it, but MMO and ATF are not designed to be part of the combustion process.

Stanadyne Lubricity Formula every tank.

I don't know about Seafoam, a buddy ruined his Ford 6.0L diesel with Seafoam, but maybe he ran a gas version instead of a diesel version of Seafoam. Of course, the 6.0's were slightly flawed to begin with, from what I am told.

I use a product called Archoil. Great product. My 6.0 runs like it was new. I use it in my wifes gasser too. Great product. Check out their website at:

http://www.archoil.com/index.cfm/product...ction-modifier/

This is a fact for the Ford 6.0's. I was fighting a stiction issue, beginning at about 165k, and was really bad during cold weather. I started using T-6 Rotella w/Archoil and its not the same truck. The coldest day of the year it will fire right up without the slightest bit of stiction. I firmly recommend Archoil and there related products.

What he said.