I have a 1994 Ford Ranger with a V6 4.0 Liter engine. My transmission was knocking hard when I went up to 55 mph, then let off the gas, and then gave it the gas again. This was usually in heavy traffic. I figured it was used up, since the truck had 175000 miles on it. I tried Slick 50 for about 10000 miles and had the same problem with no noticeable change. Two transmission shops told me I needed a new or rebuilt transmission, the price was going to be 2500 for new + labor, and 600 + labor for a rebuilt. I decided it was worth trying Lucas before I changed it because one of my friends told me about it. Within 50 miles it was acting much better, and at @ 100 miles it was shifting like new. I figured it was a temporary fix, and might get me to 200000 miles. I now have greater than 282000 miles on the truck, and I use Lucas products in all my vehicles, and tell everyone what great products they are. I'm now shooting for 300000 miles plus!