Anything I use I always dilute with water. I get an empty shampoo or dish soap bottle and squirt a little soap in the bottom then fill the rest with water. It works just fine, saves you money, and is a lot easier to get rinsed out. I think rinsing is the key to a good bath. I also use a Zoom Groom (google it) to scrub with. You can pick them up just about anywhere. It's like a rubber curry with longer rubber nubs. Works wonders and they seem to love it.
Riding: The art of keeping a horse between you and the ground. ~Author Unknown