Is it OK to mix transmission fluids?

Answered by Jarrod Smith

Mixing transmission fluids is generally not recommended. Each type of transmission fluid is specifically formulated for a particular type of transmission and has unique properties that are necessary for proper functioning. Mixing different types of transmission fluids can lead to a variety of issues and can potentially damage your transmission.

There are different types of transmission fluids available on the market, including automatic transmission fluid (ATF), manual transmission fluid (MTF), and continuously variable transmission fluid (CVT). Each type is designed to work with a specific type of transmission and has its own set of characteristics.

ATF is commonly used in automatic transmissions and is formulated to provide the necessary lubrication and hydraulic properties for the transmission to operate smoothly. It contains additives that help reduce wear, maintain proper friction characteristics, and keep the transmission clean. Using ATF in a manual transmission or CVT can cause excessive wear and damage to the transmission components.

MTF, on the other hand, is specifically designed for manual transmissions. It has a different viscosity and additive package compared to ATF, providing the necessary lubrication and protection for the gears and synchronizers in a manual transmission. Using MTF in an automatic transmission or CVT can cause issues with shifting, clutch engagement, and overall performance.

CVT fluid is specifically formulated for continuously variable transmissions, which operate differently from traditional automatic or manual transmissions. CVTs use a belt or chain system to provide an infinite number of gear ratios, and the fluid is designed to provide the necessary friction and cooling properties for this type of transmission. Using CVT fluid in an automatic transmission or manual transmission can cause slipping, overheating, and other performance issues.

It’s important to note that some newer vehicles may have transmissions that require a specific type of fluid, such as a specific brand or a specific specification. In these cases, it’s crucial to follow the manufacturer’s recommendations and use the specified fluid to ensure proper operation and avoid potential warranty issues.

Mixing transmission fluids can also lead to fluid degradation and loss of performance. The different additives and properties in each type of fluid can interact in unexpected ways, resulting in reduced lubrication, increased wear, and decreased overall performance. Additionally, mixing fluids can lead to foaming, which can cause air bubbles to form in the fluid and result in reduced hydraulic pressure and poor shifting.

In some cases, mixing transmission fluids can result in immediate damage to the transmission. For example, using ATF in a CVT can cause the belt or chain to slip, resulting in severe damage to the transmission. Conversely, using CVT fluid in an automatic transmission can cause the clutches to slip and lead to transmission failure.

It’s always best to consult your vehicle’s owner’s manual or contact the manufacturer to determine the proper type of transmission fluid for your specific vehicle. Using the wrong transmission fluid can have serious consequences and may void any existing warranties.

It is not recommended to mix transmission fluids. Each type of transmission fluid is designed for a specific type of transmission and has unique properties that are necessary for proper functioning. Mixing different fluids can lead to a variety of issues, including damage to the transmission components and reduced performance. Always follow the manufacturer’s recommendations and use the specified fluid for your vehicle to ensure optimal performance and avoid potential problems.