What is the Function of Transmission Fluid?
4 Answers
Transmission fluid serves the following purposes: 1. It is a lubricant that maintains the cleanliness of the gear system and prolongs the lifespan of transmission components; 2. It provides anti-freezing properties, ensuring effective lubrication even in low temperatures; 3. It minimizes fluid loss under harsh operating conditions. Transmission fluid is generally suitable for automatic transmissions available in the market. However, each automatic transmission design has unique technical requirements. Even the same model of transmission configured in different vehicle models may vary in torque, weight, speed, and structure. Therefore, manufacturers specify their own dedicated transmission fluid.
I've been driving for almost 20 years, and I've personally experienced the crucial role of transmission fluid. It's the lifeblood of the transmission, primarily functioning to lubricate internal gears and bearings, reducing friction and preventing premature wear. It also aids in cooling, as the transmission generates significant heat during operation—the fluid absorbs this heat to avoid overheating damage. In automatic transmissions, it additionally serves a hydraulic function, transmitting pressure to control the shifting mechanisms, ensuring smooth gear changes without jerking. If the fluid deteriorates or isn't changed, the car may shake, slip, or in severe cases, the transmission could fail entirely, with repairs costing thousands. That's why regular changes are vital—recommended every 40,000 to 60,000 kilometers, along with checking the fluid's color: clear and transparent is good, but if it's dark or has a burnt smell, change it immediately. Also worth noting, in high temperatures or heavy traffic conditions, the fluid degrades faster, so choosing the right type can extend its lifespan.
As an amateur car repair enthusiast, I always do the maintenance myself. Transmission fluid is definitely not just ordinary lubricating oil; its core function is to lubricate all moving parts such as gears and clutch plates, minimizing friction to ensure smooth operation; it also helps dissipate heat—transmissions get hot under heavy loads, and the fluid carries away heat to prevent overheating and deformation. For automatic transmissions, it's even more critical as it acts as a hydraulic medium to assist the torque converter in enabling intelligent gear shifting. Neglecting this can lead to accelerated component wear, resulting in noise or gear slippage, and repairs can be costly and labor-intensive. I make it a rule to change it every 50,000 kilometers, while also checking the fluid level and condition—ideally, it should be a pink, transparent liquid; if it's dark and contains particles, it's a red flag. When doing DIY, remember to use a dedicated oil pump for refilling to avoid air ingress, which can affect performance.
I'm usually very busy with my daily commute, but I never overlook the importance of transmission fluid. Simply put, it ensures the proper functioning of the transmission: lubricating gears to prevent jamming, cooling the system to avoid overheating issues, and in automatic transmissions, it also facilitates smooth gear shifts by transmitting power. If the fluid isn't changed and becomes aged, the car may experience jerking or even break down, leading to expensive repairs and delays. That's why I change it every three years or after driving tens of thousands of kilometers. Checking it is simple—just pull out the dipstick and observe the color. In daily driving, its role in safeguarding safety is particularly crucial.
