Do I need to flush my CVT transmission fluid?

In most cases, a full CVT fluid flush is not necessary. The standard and widely recommended service is a drain-and-fill, and you should only pursue a flush if your vehicle’s manufacturer specifies it or a qualified technician identifies a compelling reason based on diagnostics.

Understanding CVT fluid and what a flush entails

CVT (continuously variable transmission) fluid is specialized hydraulic lubricant designed for the belt-and-pulley mechanism that a CVT uses. A “flush” typically involves using equipment to push new fluid through the entire transmission, attempting to replace virtually all of the old fluid. Because CVTs operate with tight tolerances and rely on precise fluid properties for cooling, lubrication, and actuation, a flush can sometimes disrupt seals, deposits, or the delicate balance of fluids that certain designs rely on. For many models, manufacturers do not require a flush and may even warn against it unless explicitly indicated by service documentation.

What manufacturers generally recommend

Automakers publish model-specific guidance for CVT maintenance. While specifics vary, the following points capture common themes you’ll encounter in owner manuals and service bulletins:

• Use only the CVT fluid specification approved by the manufacturer; many CVTs require a fluid that is not interchangeable with standard automatic transmission fluids.


• Drain-and-fill is the usual method for CVT service, replacing most of the old fluid without forcing a backwash through the system.


• A full flush is typically recommended only if the manufacturer explicitly calls for it, or if diagnostics reveal contamination or degraded fluid that a drain-and-fill cannot address.


• Have any flush performed by a technician trained in CVT maintenance with the proper equipment and procedures suited to your specific vehicle.

Bottom line: always follow the service procedure outlined in your vehicle’s official documentation, and use fluids and equipment approved by the manufacturer to minimize risk.

How to decide for your vehicle

To tailor the decision to your car, consider these steps and consult a professional if you’re unsure:

1. Check the owner’s manual or dealer service information for the prescribed CVT fluid service method and interval.


2. Confirm the exact CVT fluid specification (brand, viscosity, and any additives) and ensure the service uses OEM-recommended fluids.


3. Evaluate driving conditions and vehicle age: high heat, frequent towing, or aggressive driving can affect CVT fluid life and maintenance needs.


4. Ask a CVT-certified technician for a diagnostic to determine whether a drain-and-fill suffices or if a flush is warranted in your case.

Following these steps helps prevent unnecessary procedures, reduces the risk of CVT damage, and ensures the fluid system remains properly lubricated and cooled.

Summary

In short, a full CVT fluid flush is not universally required and is not universally safe. For most vehicles, drain-and-fill is the standard approach and will typically replace the majority of the old fluid without the risks associated with a complete backwash. Only pursue a flush if the manufacturer explicitly requires it or a trained technician recommends it based on diagnostics and your vehicle’s condition. Always reference the official service guidance and use the prescribed CVT fluid, then consult a CVT-specialist if you have any doubts.

Does a CVT transmission need to be flushed?

Yes, you should change the fluid in a CVT transmission, but a drain and fill is generally recommended over a full flush. A flush can potentially dislodge harmful debris and clog narrow passages in a CVT, especially in high-mileage or older transmissions. Therefore, changing the fluid is crucial to prevent damage and ensure longevity, but it should be done through a drain and fill or multiple drain and fills to replace most of the old fluid.
 
This video explains the difference between a transmission fluid change and a flush: 47sFixITYouTube · May 25, 2025
Why changing CVT fluid is necessary

• Fluid breakdown: Over time, CVT fluid degrades, becoming less effective at lubricating and cooling the transmission. Skipping changes can lead to serious and expensive problems. 
• Performance issues: Dirty fluid can cause symptoms like surging, delayed acceleration, and rough shifting, which can be signs that the fluid needs to be changed. 
• Manufacturer recommendations: Most manufacturers recommend changing the fluid every 30,000 to 60,000 miles, although this can vary depending on the vehicle and driving conditions. 

Why a drain and fill is preferred over a flush

• Risk of dislodging debris: A full flush can force new fluid through the system, which may dislodge metal filings, sludge, and other debris that can then clog narrow passages in the transmission, leading to damage or failure. 
• Contamination risk: A flushing machine may be contaminated with residue from other vehicle services, and the high pressure can force fluids through circuits not designed to handle it. 
• Drain and fill: This method is less invasive and is the standard procedure recommended in factory service manuals, ensuring a more complete change over multiple cycles if needed. 
• Frequency: If the vehicle has never had its fluid changed, or if you are unsure of its service history, a drain and fill is the safer option. 

This video shows what happens when you change lifetime transmission fluid: 1mScotty KilmerYouTube · Sep 5, 2022
When to consider a flush

• Some sources suggest a flush can be beneficial for high-mileage vehicles or those with severe shifting problems, especially if they have never had a fluid service before. 
• It's important to consult a trusted mechanic to decide if a flush is the right option for your specific situation. 

How often should CVT fluid be flushed?

every 30,000 to 60,000 miles
How often does Nissan recommend CVT transmission fluid be changed? Nissan recommends CVT transmission fluid be changed every 30,000 to 60,000 miles, depending on driving habits and conditions.

How do I keep my CVT transmission healthy?

Do the drain and fill regularly, drive gently when changing speed, go easy on hills, and if you are driving a long distance take breaks to let the transmission cool off for a bit.

What happens if I don't change my CVT fluid?

If you don't change your CVT fluid, it will break down over time due to heat and friction, leading to a range of problems including overheating, slipping gears, delayed engagement, and rough shifting. Eventually, this can result in catastrophic transmission failure, requiring costly repairs that often exceed the cost of regular maintenance by thousands of dollars. 
How neglecting CVT fluid causes damage

• Fluid breakdown: The fluid loses its lubricating and cooling properties as it gets old and contaminated with wear particles. 
• Overheating: Without proper cooling, the transmission overheats, which causes internal damage. 
• Increased wear: Old, dirty fluid can't protect the metal parts inside the transmission, leading to accelerated wear on gears and other components. 
• Performance issues: The transmission may start slipping, shift poorly, or have delayed engagement. 

Consequences of not changing the fluid

• Increased risk of failure: The gradual damage from old fluid can lead to complete transmission failure. 
• Expensive repairs: Replacing a failed transmission is a major expense, far greater than the cost of regular fluid changes. 
• Reduced performance: Even before total failure, you will likely notice a decline in performance and shifting quality.