In my experience I have found that most products that work great on Gasoline engines, don't work well with Diesel engines, and vice versa. My concern is the same with Seafoam. It claims to work great with both engines, but I am skeptical.
It truly is great stuff!! I have used it to pre-fill diesel fuel filters to clean the injectors, and make it easier to bleed. It is also a great carbon cleaner, and works well to remove moisture from fuel. I used it in my kubota diesel over the winter to make sure it would keep starting. And it did without being plugged in at 15* below zero F. They also have a couple other good products. One is Deep Creep. It is basically seafoam in an aerosol can. Easier to spray into intakes for cleaning carbon. It also as the name implies is a great penetrant. It works really well if you slightly heat the seized nut to aid the creeping effect. They also have a product called Trans Tune, which is great for cleaning up automatic trannys. But it will also work in hydraulic systems to remove moisture build up before changing fluid. Then when added to the new fluid it will help to restore seals, and aid the lubrication of the hydraulic pump.