Why can CVT only use gravity oil change?
2 Answers
Due to the complex internal structure of traditional automatic transmissions, including the torque converter and 'mushroom head' mechanism, the specific situation is as follows: 1. Gravity oil change: Simply using gravity oil change cannot effectively drain the old oil, so a circulation machine is required for oil change. 2. Others: CVT, on the other hand, uses two trapezoidal pulleys and a steel belt for speed variation, and its internal structure is not as complex as traditional transmissions, so gravity oil change is sufficient. Additional information: The internal mechanism of CVT transmissions is indeed slightly simpler than traditional AT transmissions, but there are still many areas inside CVT transmissions where dirt can accumulate, and simply using gravity oil change cannot effectively drain the old oil. The same principle applies to dual-clutch transmissions.
I've driven several CVT-equipped cars and deeply understand why only gravity oil changes are recommended. It's determined by the core design of the continuously variable transmission – the steel belt and pulleys inside are extremely delicate, as vulnerable as precision watch mechanisms. If high-pressure flushing machines were used, the forceful oil flow might dislodge deposits that could clog oil passages or damage components, leading to slippage or malfunctions. Gravity draining relies on natural outflow, replacing only the old oil at the bottom (about 4-6 liters) without disturbing the entire system. Additionally, CVT fluid requires high viscosity and cleanliness. The gravity method is gentler, preventing accidental wear and extending service life. I've noticed all manuals emphasize this approach – it's the preferred maintenance choice for worry-free protection.
