We recommend a 40,000 mile interval on filter and fluid to extend the life of your transmission. We also recommend, especially on ZF transmissions, to perform a preventive shift quality service to further extend the life and also to avoid a breakdown. Check out this in shop video of a 6HP valve body we currently serviced.
This vehicle was experiencing shift quality issues and was stuck in limp home mode. Most shops will just replace the whole transmission. We have proprietary procedures and tooling to test the mechanical portion of your transmission and determine whether or not you need a transmission, a whole valve body with a control unit, or just a freshen up service. This particular valve body is also getting a full solenoid pack kit as well. Everything but the control unit is being replaced. We did give the customer both options considering the mileage.