Ask your service writer how the automatic transmission world possibly survived for decades prior to the invention of the power flush machine! He’s right, a drop and drain doesn’t get everything out, but it doesn’t have to, unless your transmission is having a problem. It is no surprise that the dealer’s pushing unneeded services, that’s what stopped me from going to my Lexus dealer. The service writer insisted that the tranny fluid be changed every 15,000 miles!