Why Do 4S Shops Only Use Gravity to Change Transmission Fluid?
1 Answers
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: A circulation machine injects new fluid while extracting the mixed old and new fluid, achieving a high replacement rate and more thorough change. However, it consumes more fluid, is relatively wasteful, and incurs higher costs. For a car that has been used for a long time with high mileage and hasn't had its transmission fluid changed for an extended period, the transmission will accumulate certain sediment impurities during operation. These impurities flow with the transmission fluid, sticking to the torque converter, hydraulic valve body module oil passages, or settling in the oil pan and transmission filter. The longer the time, 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 overheat friction surfaces, causing unnecessary power loss. Conversely, if the viscosity is too low, centrifugal force may fling the fluid off gear surfaces, leading to oil seal leaks and potentially resulting in insufficient lubrication on gear surfaces. This increases wear and may even cause sintering. Therefore, selecting the appropriate viscosity is essential. When changing the fluid, refer to the car's user manual or maintenance manual.