I've used Chevron Techron in a '77 300D. The label says it's ok to use in diesel engines. After using it, my fuel guage suddenly stopped sticking below 1/4 tank. Now I just use Redline Diesel fuel catalyst, a generous ounce per ten gallons. It does seem to help the engine run a bit stronger once it's warmed up.

------------------
Robert W. Roe
1984 300SD 169K mi