I have used the lucas oil stabilizer/additive, feul treatment and transmission additive in my 02 7.3L (when I had trans problems)
I have used the oil stabilizer in just about every vechile I own and I find that it helps. The transmission additive helped me get another 3 months out of already slipping transmission. I have also used some of their gear oils. I think that there products are great! No complaints here.