How to Determine Whether Transmission Fluid Needs Replacement?

[McSimon]

To determine whether transmission fluid needs replacement, a comprehensive assessment should be made based on the following aspects: Before evaluation, ensure the engine reaches operating temperature, then wait for it to cool below 50°C (requirements may vary by vehicle model). 1. Appearance and Odor: Normal ATF (Automatic Transmission Fluid) should appear clear and pure. If the fluid turns black, emits a noticeable burnt odor, or feels gritty with visible impurities when rubbed between fingers, replacement is needed. Note that due to the transmission filter, larger particulate impurities are typically trapped in the transmission pan, so obvious metal shavings or debris may not be felt, but some fibrous particles might be visible. 2. Transmission Temperature: If the transmission frequently triggers overheating warnings under similar driving conditions, this may indicate excessive impurities in aged fluid, impairing heat transfer. If engine coolant temperature remains normal, degraded anti-foaming properties of the transmission fluid could be the cause, warranting consideration for replacement. 3. Driving Performance: Excessive impurities can interfere with valve body operation, causing delayed or incomplete closure, affecting hydraulic pressure. This may manifest as jerking, surging, unusual noises, or increased operational sounds. These symptoms should be evaluated alongside the vehicle's mileage to conclusively determine if a fluid change is required.