I am with Jerry on this one. My neighbor has one of these and used it once. The 5 gallon bucket is a nice place to keep all your a/f though. It is also really nice to use when winterizing an RV, just don't trust it on a boat. I would rather pull hoses and drain plugs, remove thermo and fill block with a/f just to be sure.
Cost = 4 Gallons of a/f and $20 for thermo and gasket (or you can go cheap and just buy gasket only for $2)
Time = 60 minutes from start to finish