In case anyone is interested in cooling flushing.

This is kinda close to the post so I will add. Back in the 80’s and 90’s I was a GM master tech. That means I got all the engine and trans trouble shooting and a ton of blown head gaskets on GM. When they first went to Dexacool the orange 100,000mile coolant we did a lot of coolant leaks and head gaskets. At that time the radiators no longer were the fill point and the start of the “coolant bottle” was used. When you had a “milk shake mess” as we called them you could not clean the bottles and GM would not pay for new ones. The plastic bottle was full of nooks and crannies that would collect the mess. So GM made us go out and buy Tide laundry soap. Flush the engine with clear water till most brown junk was gone. Then add 1 cup of powdered tide and refill with clear water. Run for approx 20 mins and make sure thermostat cycled 10times. Then flush again with clear water. Then replace head gasket- that’s the best I remember of the procedure. Anyhow, it worked well. Especially on the aluminum blocked car. Dishwashing powder also works- the goal is no residue from the soap.