When to Replace: Check your vehicle's owner's manual, every 60,000 to 100,000 miles in normal condition usually, often to every 30,000 - 50,000 miles under hard condition
Note: When you replace the transmission filter, you must also replace the transmission fluid and the fluid pan gasket, Replacing just the filter or just the fluid is an incomplete service and will not provide the full benefit
About Installation: Professional installation recommended cause you need to change the fluid as well, unless you have relevant experience and patience, DIY not recommended