The service stations in my area don’t like power flushing since they are afraid of damaging the cooling system. They’d rather losena hose and drain it out. I don’t necessarily believe that myself. A reverse flush through the heater hose with a garden hose has always worked well for me. Prestone and others sell these adaptor kits. Agree if the cooling system is on its last legs it might reveal a developing leak, and the customer might think the shop caused it.