You do not need to buy the expensive Cascade Plus surfactant. You can use any clear shampoo you can find at Dollar Tree. The application rate is 3 ounces per 1,000 square feet. If you have 2,000 square feet to spray, put 6 ounces of shampoo into a hose-end sprayer, fill the jug carefully with water, and spray it out as evenly as you can over the entire yard. If you use too much, no problem. A friend of mine sprayed at 64 ounces per 1,000 and never had a problem. So spray your yard and follow that up with 1/2 to 1 inch of rain or irrigation. Wait 3 full weeks for the magic to happen. Once it does you will find that after a rain or deep irrigation the soil will become unsettlingly soft and it will return to very firm/hard underfoot when the soil dries out.
This is not my rant alone. I’m simply conveying what is well known in some of the better lawn care forums online. I did not believe in the shampoo treatment until I tried it. Before that all I knew was that core aeration did nothing for my lawn. So I spent a dollar on some cheap shampoo, and it worked way beyond my expectations. Also one treatment seems to last for many years as long as you don’t neglect watering for many weeks during a very hot/dry summer.