I use G-05. In the past I used “green”. However, after reading a post on the Brickboard from a contributor who I respect a lot I switched. He indicated that he had never had to change out a heater core or a head gasket on a car that had been using G-05 long term. That was incentive enough for me having already earned my merit badges in both categories.

I purchase full strength and dilute 50/50 with distilled water. It is criminal how much you are paying for water when you crunch the numbers on cost differences between full strength and diluted coolant.
--
Any twenty minute job is just a broken bolt away from a three day ordeal