I have a one man auger, Little Beaver Hydraulic. At 66 I can still dig a six foot deep hole in the worst clay on the planet by myself when I have to. I've only had it almost thirty years and used it just last week on a job a two man or a tractor would never have got into. I have 35' hoses for those special occasions when I can't get the power plant next to the hole. I had three laborers working with me, one with a death grip on the torque bar which is usually attached to the power unit. The secret to digging in clay is a little bit of water. I've found a 32 ounce cup full is usually all I need for a 12" X 3' hole, standard post hole. I figured that out real quick on my own. I was fighting the auger binding up and thought of maybe using some WD to lube the flights when I remembered that when the clay is wet you can't stand on it without falling down. Haven't fought it since.