It is recommended that you replace your lifters every 50,000 miles or so to ensure optimal performance. However, the exact interval may vary based on the type of vehicle and how it is used. If you drive your vehicle in a more demanding environment, such as off-roading or racing, then you should replace your lifters more frequently. Additionally, if you are noticing any signs of wear or performance issues with your engine, then it would be wise to check your lifters as soon as possible.