I drained the cooling system on my 2009 4.7L (4 cyl) Regular Cab Tacoma to replace the coolant.
I got about 9 quarts out, I can only get 6+ quarts in. I've run the truck up to operating temperature, the thermostat doesn't open. It doesn't overheat. I drove the front end up a gravel pile to 30 degrees which didn't help.