1999 Cadillac Catera Owner's Manual - Page 256

yellowblue Automatic Transmission Fluid It is not necessary to check the transmission fluid level. A transmission fluid leak is the only reason for fluid loss. If a leak occurs, take your vehicle to the dealership service department and have it repaired as soon as possible. You may also have your fluid level checked by your dealer or service center when you have your oil changed. Change both the fluid and filter every 50,000 miles (83 000 km) if the vehicle is mainly driven under one or more of these conditions: 5. Replace the filter by sliding it back in, reattaching both retaining clips and closing the grille flap. 6. Replace the engine compartment rear seal. 7. Close the engine hood. For the type of filter to use, see "Normal Maintenance Replacement Parts" in the Index. D In heavy city traffic where the outside temperature regularly reaches 90_F (32_C) or higher. D In hilly or mountainous terrain. D When doing frequent trailer towing. D Uses such as found in taxi, police or delivery service. If you do not use your vehicle under any of these conditions, the fluid and filter do not require changing. 6-18