Bought my truck with 187k miles on it. The truck was having injector striction problems for the first 5-10 miles of cruising at about 45 MPH. I changed all the filters and the oil to Rotella T6 5w40 and that reduced it to about 1-2 miles of striction and still hard starts first thing in the morning. Day before yesterday with 500 miles on the new oil changed I added 2 containers of rev-x to the oil and now after less than 100 miles it starts beautifully, has no striction, and runs smoother overall. :woot: I am extremely pleased with the product and will continue to use it!! Now to take care of all the other dreaded problems these 6.0's have!!!