The auto trans in my restored 88 GMC pickup began to refuse to up shift over a year ago. Being informed of a two week wait to get it overhauled at the local tranny shop, I decided to try a bottle of Lucas transmission fix with "nothing to lose".
Since it was cold and raining, I left the truck running, in neutral, with the emergency brake on. I added less than half of the bottle in the parking lot of the auto parts store intending to return home and warm the remaining additive for easier flowing.
Pulling out on the highway, the truck immediately up shifted normally and has been trouble free ever since! With only about 1/3 of the bottle having been added, AMAZING!
As a preventative maintenance measure, I have added a half bottle to all our other automatic transmission vehicles. Great stuff, LUCAS!