Why Do 4S Shops Only Use Gravity to Change Transmission Fluid?

[EloiseLynn]

4S shops only use gravity to change transmission fluid because they lack a circulation machine, requiring a complete replacement at once. Here are the relevant explanations: 1. Cost: Using a circulation machine to change fluid involves injecting new fluid while extracting the mixed old and new fluid, resulting in a higher replacement rate and more thorough fluid change. However, this method consumes more fluid, is relatively wasteful, and incurs higher costs. For a car that has been used for a long time and has high mileage, prolonged failure to change the transmission fluid leads to the accumulation of sediment impurities in the transmission. These impurities flow with the transmission fluid and adhere to the torque converter, hydraulic valve body module oil passages, or settle in the oil pan and transmission filter. The longer this persists, the more they accumulate. 2. Appropriate Viscosity: It is crucial to choose transmission fluid with the right viscosity for replacement. If the viscosity is too high, it can cause overheating of friction surfaces, leading to unnecessary power loss. Conversely, if the viscosity is too low, centrifugal force may fling the fluid off the gear surfaces, causing oil seal leaks and potentially resulting in insufficient lubrication on the gear surfaces. This can increase wear and even lead to sintering. Therefore, selecting the appropriate viscosity is essential. When changing the fluid, refer to the car’s user manual or maintenance manual.