On our 2016 Explorer 2.3 EB. Went to start doing drain/fills on the untouched factory Motorcraft orange coolant, only 45k miles but it’s been 6 years. I pulled the radiator drain plug and got out, at most, 3.0 quarts out of the 11.6 quarts the book lists. It seems like most vehicles will drain at least half of the total capacity through the radiator drain. Why did I get such a small amount out? The drain is at the lowest point in the system, and the radiator, reservoir, and all hoses surely have more than 3 quarts in them. Are there various check valves along the way or something? Just trying to understand it better. Anyway, from now on I’ll just suction out the reservoir and replace the fluid a couple times a year, as it’s much easier than pulling the plug and will get nearly the same amount of fluid out.