homemade carpet shampoo solution

A friend gave me this and he is a stickler for clean and effective! (or affective?) Use 2 scoops of Oxyclean powder or off brand to 2 qts boiling water. Add to shampooer and add more water to fill tank. Does not buy the expensive shampoo sold w/ the rentals. I found those shampoos so greasy or oily. To the high traffic area he sometimes uses a commercial spray solution; just a tad.