A few years ago I also read the results of this testing. It was an eye opener. Until then, I had been using Marvel Mystery Oil as a diesel fuel supplement, based on my previous positive experiences with the product in gasoline motors. According to the testing, MMO and some other additives, actually degraded the lubricity of the fuel itself.

I have four diesels, one truck and three farm implement types, of which all are "old school" with mechanical injectors and pumps. Except for one fuel jelling incident in very cold weather with a tractor, I have never had a maintenance issue with any of them. Because they are expensive to purchase and replace, I try to maintain them as well as possible.

I have switched to synthetic two stroke oil mixed with the fuel as a lubricant. I also use Sea Foam in the colder winter months, and a Cetane booster in the summer when the truck is being used to tow.

I can't say that these additives have prolonged the lives of my equipment, even though that is the reason for their inclusions. Diesels, with a minimum of maintenance, are long lived. I can only say that I have had zero maintenance issues during my present and past diesel ownership, which has spaned several decades. When I run the cetane additive, I do notice a slightly "peppier" performance. This is a seat of the pants observation, and not one based on statistical facts.

I will continue to spend a few extra dollars at every fueling with the additives, in hopes that the reliability of my equipment will continue to be exemplary.

I grew up listing to a father that kept telling me that a detriot had spent millions designing a car and I was spend $1.95 to mess it up.

I have no problem with additives and do add some to my diesel fuel. Especially in the cold weather to prevent gelling. I spent several weeks in North Dakota this winter and got to experience first had -25°F temps. Saw many many diesel trucks never get turned off for days at a time in fear they would never restart in that cold.

My thoughts keep going back to what my father told me as a youth. So I take more an atitude that if I'm going to add something, I will add something that was designed and engineered to solve the problem I am worried about.  I don't believe is using waste transmission fluid in diesel fuel or two cycle oil etc.  If I want to improve cetan, I buy a cetan improver, If I want to prevent gelling, I buy a product designed to prevent gelling.  In todays world, manufactures have spent millions developing products and marketing them to solve certain problems. I personally don't believe I have the knowledge to substitute other products and achieve as good of results.

The Diesel Power study was conducted 5 years ago in 2007 when ULSD first came to market. And it showed how some products worked better than others. I wish somebody would conduct a more current version of that study. A 2012 version. Since many products have updated their products since 2007 and new products have come to market. I suspect some companies have just combated the mediocre press they got in the study by saying it was 2007 version of their product and a newer product is available.

The new diesel trucks have become so fine tuned and the tolerances so high that small things can cause very expensive repairs.  Both Ford and GM use a High Pressure Fuel Pump (HPFP) that has been beaten to death in the diesel forums.  The rumur seems to be that these pumps are working on the edge of what today diesel fuel can lubricate. So it has become a common war cry to add a lubricating additive to the fuel to protect these HPFP. So I look for an additive that claims to add Lubrication, Cetan boost,  in the winter Anti gell qualities.

By using an engineered product, I can read the lable and see instructions on how much to add. There is no guess work.  Is 2 oz not enough and no better than running straight fuel, Is 2 oz to much and causing some other part to gum up? The problem with two cycle oil, Is that it is designed for a 2 cycle engine, There are no instruction or detailed engineering stating that it was designed to solve lubricating problems in HPFP of modern diesel engines. If the manufactures would like to test it for the purpose and release detail findings, I would be happy to consider it, But until they do, I happy buying other products that state on their labels that they were designed to solve the problems I'm concerned about.