I have an 1987 Gmc V1500 4x4 with 175,000 miles on it.For a couple of years now the 700r4 transmission has been sluggish and recently hasn't been shifting properly.For the past 5 years i've even changed the transmission fluid every 10,000 miles.Finally i decided i've put up with it long enough.Checking on new rebuilt transmissions at around 500 bucks i decided that wasn't an option considering the truck isn't worth that kind of money.I stopped at the local auto parts store and seen the Lucas Transmission Fix additive and decided to try it with a transmission filter change.I couldn't believe it!! After installing the new filter and tranny fluid with the Lucas addittive, the transmission felt like it was new again!!It wasn't sluggish on take off anymore and shifted through all the gears perfectly with no hesitations or hard shifts.I still can't believe that an additive can have such a dramatic affect on a transmission!!At first,i was skeptical when i bought the Lucas Transmission Fix but now i'm a believer!!Such a small price to pay for having a good working transmission again.I'll probably get many more years of use out of my truck again!Thanks Lucas Oil!!!