No Transmission is ever sealed for life!
Most vehicle manufactures today tell us that the automatic transmissions in most modern vehicles are ‘filled for life’ or ‘sealed for life’ on the assembly line and never need servicing. Taking that advice on face value is attracting disaster. There is no such thing as a ‘sealed for life’ transmission.
In recent years vehicle manufacturers no longer stipulate servicing of the transmission in the service schedule. This makes the vehicle appear to be cheaper to run and reduces maintenance costs, resulting in a more attractive vehicle to fleet buyers (being the manufacturer biggest customers). The manufacturers of the transmissions, however, still strongly recommend they are serviced regularly.
Every transmission from every manufacturer can be un-sealed and re-sealed and every transmission requires regular servicing to prevent problems occurring in the future.
If you want your transmission to continue to give reliable performance, then forget the ‘filled for life’ mentality and have your transmission checked annually including replacing the transmission fluid and filter. Regular servicing will extend the life of your transmission, avoiding an expensive repair bill by the time your car is undoubtedly out of warranty with the manufacturer.