Why can't CVT use a circulation machine for oil change?
4 Answers
Cvt using a circulation machine for oil change will increase the amount of transmission oil used, thereby raising the cost, so it is not recommended to use a circulation machine for CVT oil change. Here is more information about transmission oil change: 1. One method is the traditional gravity method to drain the oil, which has the same principle as changing engine oil. It involves loosening the transmission's drain screw to release the oil and then refilling with new oil. 2. Another method uses a circulation machine to change automatic transmission oil, mainly utilizing the machine's pressure to dynamically replace the oil in the torque converter's lubrication pipe and cooling pipe. 3. When using a circulation machine for oil change, the oil pump continuously pumps new oil into the transmission while the suction pipe continuously draws out the old oil from the transmission's drain port. By controlling the amount of oil added and drained to be equal, the total amount of oil inside the transmission is maintained. This process requires a large amount of transmission oil, resulting in higher costs.
I've worked in auto repair shops for many years and often encounter the question of why CVT transmissions can't use a flush machine for fluid changes. Simply put, CVT designs are too delicate—they operate on steel belts and pulleys rather than the sturdy gears of traditional automatic transmissions. Flush machines use high pressure to force new fluid in while flushing out old fluid and debris, but CVTs have tiny oil passages and components. High pressure can easily clog debris or damage parts, leading to transmission slippage or failure. I've seen many owners risk cheaper flush services only to face terrifyingly expensive CVT repairs afterward. CVT fluid is specialized; incomplete mixing compromises lubrication. I recommend the drain-and-fill method: remove old fluid first, then add new fluid—doing it in stages ensures thoroughness. Safety always comes first—don’t take this risk.
As a regular CVT car owner, I was also curious about why a flushing machine couldn't be used for oil changes. Later, I learned from a mechanic that the high pressure from the flushing machine could damage the fragile internal structure of the CVT, potentially harming the cones or chains. For example, a friend of mine used it once, and the transmission started making strange noises, costing over a thousand dollars to fix. Gravity oil changes are simpler: after warming up the car, just loosen the drain plug to let the old oil flow out naturally, then add new oil. Although it doesn't remove all the old oil, doing it multiple times works. Always buy genuine CVT fluid—don't skimp on that. Pay attention to your car's maintenance manual and change the oil regularly to maintain performance.
As a car DIY enthusiast, I learned at the exchange meeting: The reason to avoid using a flush machine for CVT transmission oil changes is primarily due to pressure issues. The flush machine forcibly injects new oil for cleaning, but the CVT has an internal hydraulic system. If the pressure becomes unstable or air bubbles are introduced, it can damage the steel belt mechanism. Gravity oil changes are safer—simply remove the oil pan drain plug to drain the old oil and add new oil. It's recommended to do this every 30,000 kilometers, and it's even better to replace the filter at the same time. CVTs are particularly susceptible to contamination, and improper flushing can lead to premature wear. I always stick to regular maintenance to extend its lifespan.
