Step 3 is where you lost me. You say to refill the coolant system until full.3. Once completely drained, replace the spigot, and remove the coolant cap completely. From here, put in your favorite coolant system flushing detergent (For me, it's usually Prestone Super Flush), and, slowly refill the coolant system with cold water until full.
What container are we refilling? The radiator or coolant reservoir?
If you meant to refill the radiator, then where is the cap located?
If you meant the coolant reservoir, how do we know the coolant being poured in the coolant reservoir is fully filling the radiator? How do we know the hose from the coolant reservoir to the radiator didn't get clogged half way through filling it?
On the surface, this appears to be somewhat dangerous.
Any advise would be greatly appreciated! Thank you!