First off, I don't know anything about actual radiator flushes. I just had the local Chevy dealership flush the radiator on my 2008 GMC Sierra 1500. How exactly do they go about flushing the radiator? It doesn't appear that they even touched the lower radiator hose, and I know these radiators didn't come with a drain. The upper radiator hose and the hose from the reservoir to the radiator appears to have been touched and used. I normally do all of my own maintenance, but I didn't want to deal with the mess and hassle on this job. Just making sure I didn't get "hosed" by the dealership.