Recently I went to a fairly good workshop to get the coolant changed. After draining the coolant, the mechanic ustaad insisted to not put coolant and only use tap water. I was like
I told him to stay away from my car, kept my car there, took out the coolant bottles from trunk, asked him to give me all the tools and just stand there and see the correct procedure and why we put coolant, browsed and read up on internet about correct procedure about filling and dilution quantities, changed the coolant myself, drove back to home.
I am always going to change the coolant myself