I have used Lubegard products in the past. I have tried the Lubegard for engines, the power steering supplement, and the transmission supplement.
I am convinced that the power steering supplement works. I had a problem during cold mornings with the power steering making whining noises. I put Lubegard power steering supplement in the power steering fluid and it did stop the noise in my car. I can't speak for anybody else.
I have had manual transmissions for a long time and I can't really say much about the transmission supplement. It is made mostly for automatic transmissions although you can put it in manual transmission fluid. But I will tell you one thing-go to a lot of automatic transmission repair shops and a lot of those shops use Lubegard.
The first time I ever tried the engine supplement it seemed like my car ran much smoother. I was impressed at the time-but then I decided that even if it works it is too expensive to be adding every oil change.
I used to be interested in and use some engine oil supplements but I have moved away from that. I think a person is better off using a good motor oil, good oil filters, and good air filters and leaving the oil supplements alone. About the only stuff I believe in now is Auto-RX, Neutra, and Schaeffer's 132. I will not put anything else in the engine. I would rather use a good motor oil like Schaeffer's Oil and forget about most of the oil supplements.