Pull the lower hose, it is quicker and easier but be warned. If you remove it from the radiator side do not pull and twist with all your might. You will crack the radiator. And they ain't cheap. Take it off the block if you can, much safer. I like to remove the upper hose at the same time so I can reverse flush the radiator. I take a water hose and duct tape it into the lower hose and turn on the water. It seems to keep the thing fairly clean. I never use any type of aftermarket flush as I have had many experiences with such products. I only windup with more headachs than what I started with..