I'm at 5 years now on my 2014 Z51. I guess it's time to change the coolant. I haven't seen any how-to threads so I thought I would ask for any tips or warnings. It looks like my petcock is on the driver's side of the radiator at the bottom but there is an opening in the bottom near the petcock that looks like a drain aimed straight down. If the hole is the drain then kudos to the engineers for making it easy to drain without spilling. I assume that the valve only turns 1/4 or 1/2 of a turn counterclockwise to open. Can anyone confirm this? I don't expect to get a full drain by just opening the valve with the thermostat closed; am I correct? Since it is a sealed system, my thought was to open the valve, add water to the reservoir and start the engine. Keep adding water until it is flowing clear, then start adding the 60/40 Dexcool mix until I see a change from clear to red. Am I overthinking this? Does this method make sense? Is there an easier/better way? Thanks in advance for your help. I enjoy doing the basic maintenance on the car and I've gotten a lot of great advice from the forum that has made ownership much more fun.