Flushing A Transmission
Flushing a transmission is one procedure common at many fast oil change shops that we wish would go away. It's dangerous. A technician hooks up a machine to the cooler lines coming out of the transmission and backwashes the fluid out of your transmission. It does a good job of replacing all of the fluid in the transmission with new fluid. But the collateral damage can cost you. Backwashing is a good way to clean your swimming pool filter--they're designed for it. But in your transmission, you're more likely to disloge bits of metal and varnish and have them wind up somewhere like the valve body where they don't need to be. This can spell trouble soon down the road. In fact, we do a fair amount of business repairing transmissions that have recently been flushed elsewhere.
We recommend a routine fluid service, which, on most vehicles means droping the pan (except on vehciles where there is no pan, like Hondas) , cleaning the pan, adjusting any bands (which isn't done on with a flush), replacing the filter (also ignored during the flush), and refilling the fluid. About a quart or two of old fluid remains, but most of the fluid is new.
We always first perform a Free Diagnostic to be sure that the transmission is healthy enough to be serviced. Servicing a transmission is a maintenance procedure, not a repair procedure. Few, if any, problems will be solved by a service. So if you're having a problem, even a service is a waste of money. We do the diagnostic first to be sure you don't waste your money.. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .