When it comes time to care for your Subaru’s complex electronically controlled Constant Variable Transmission (CVT) it can be confusing depending on who you ask. Subaru has been using the CVT Transmission in it’s lineup since 2010. This was it’s second attempt at using the CVT technology in the They first introduced the CVT in the 1990 Subaru Justy. Unfortunately, due to a high failure rate, it was a short lived experiment. Subaru dropped the program after ’94 along with dropping the Justy from the US lineup. The CVT was a great idea back in 1990 and Subaru thought it was going to change the paradigm of transmissions as we know them. Essentially it was an automatic transmission that, through it’s unique design, would offer the same fuel mileage as a manual transmission with the convenience of an automatic. The concept was great but the engineering for long term use wasn’t. Back in my dealer days, we were replacing Justy CVT transmissions under warranty quite frequently. As a matter of fact that they failed so often that if you saw one that went over 60,000 miles, it was a miracle in and of itself.  Many of the owners converted those Justies over to manual transmission cars with wrecking yard parts just to keep them on the road.

    Fast forward to 2010 and now that other manufactures had proven success with CVT’s (Nissan and Honda), Subaru decided to bring it back for their 2010 Legacy, and Outback models. One thing we noticed right away was the recommended service interval by Subaru. In the Subaru warranty manual, it stated that the fluid was to be inspected only but was a lifetime fluid. Over the years, as we saw CVT failures, we noticed the common theme of very worn, dirty CVT fluid. These were coming in having never been serviced and failing between 90-150k miles. It was frequent enough that even Subaru extended the warranty on many of their CVT equipped vehicles to 10 years or 100,000 miles. Knowing the price of replacement was running well over $8000, Smart Service decided to start recommending a fluid change to our own customers, regardless of what the Subaru warranty manual suggested. Science has taught us that all petroleum based fluids break down over time due to the extreme environment it’s subject to. It loses it’s capacity to protect the components that they’re meant to keep protected and lubricated. The fluid has to be able maintain a thin film of protection between metal drive belt and the pulleys it drives. This quality is called the oil’s “shear strength”. Over time this shear strength diminishes as the oil deteriorates and the result is accelerated wear between those metal components within the transmission.  

  In 2013, Smart Service started to offer our customers the the CVT fluid change as an option. Our clients valued the peace of mind that this would lower their odds of an unexpected breakdown and prevent premature wear on their $8000 transmission. When we do a drain and fill we’re only able to get 50% of the fluid changed because the rest of the fluid is trapped in the torque converter. Considering this fact, and considering how early we notice the fluid deteriorating, we recommend the change around every 30k miles (or sometimes sooner as fluid condition dictates). If we find the fluid in extremely poor condition, we occasionally perform two drain and fills back-to-back to maximize the amount of clean fluid in the transmission. We are currently working on a system to perform transmission flushes to them, much like the prior automatic transmissions. This would achieve nearly a 95% fluid exchange. We’ll keep you posted once that’s available.  

Eventually, in 2018 or thereabout, Subaru finally started recommending fluid change on the CVT in it’s warranty manual as early as 24,855 miles for severe conditions. (such as towing). I’m guessing it’s a Canadian that figured this out because it equates to 40,000km!  If you scour the web you’ll find many Subaru dealers are now recommending the 30k or 60k change interval, thus realizing that the lifetime fluid was an unrealistic expectation. Even if Subaru want’s you to trade your car in every 100,000 miles, at Smart Service we always want to provide the level of care that will get the full life cycle out of your vehicle that can easily make it to 250k and above with quality preventive maintenance. Depending on the specific CVT transmission, it can range from $250-$400 depending on vehicle specifics but compared to the alternative, it can be a great investment into the longevity of your vehicle.

Stay tuned for updates on when we have the full CVT Flush procedure available. 


Mike Corbin, Owner.



  1. JJ
    October 24, 2023 Reply

    Thank you for the great article explaining Smart Service’s CVT strategy and proactive approach.

    In trying to previously understand and see how it compared a year ago I reached out to SOA and a number of the local dealerships. Back then I was still being told by SOA and local service departments that SOA considers the CVT fluid a lifetime fluid, but that it should be inspected and changed out when needed. I did find one local dealership however recommending doing a 7-qt drain and fill every 100k and general recommendations of doing this every 60k in the Subaru forums. I certainly questioned the idea of a lifetime fluid, but how often it should be done was very confusing. The article did a great job explaining the history and reasoning behind Smart Service’s CVT maintenance approach. It is still a little more aggressive than others, though it sounds like they are moving that way. It is clear in the article one is spending hundreds to save thousands.

    With the increase in CVT fluid change, any projection on lifetime range one should now expect to get on this type of transmission? Any estimate when the CVT flush might be available? Once available, will you have a recommended interval for it to be performed?

    • Mike Corbin
      October 24, 2023 Reply

      Thanks for the reply JJ. We’re still learning how far they’ll go since they started using them in 2010 but we’re seeing some of our customers with mileage over 180k now and still performing well. In the long run , preventive maintenance is a proven method saves far more $ over the life cycle of the vehicle than the approach of fix it when it breaks. Much like the human body! Just like a person that wants their body to be at it’s best and last the longest, they’re eating healthy, exercising and getting plenty of sleep to prevent or delay the onset of disease and breakdown of the body.

    • Sarah in CA
      October 24, 2023 Reply

      Thanks for this… my son is buying a 2012 Imprezza and this is obviously a concern but he really likes the car enough to deal with this risk.

      I told him we can get the transmission fluid changed right away to make sure sure it’s fresh and see what color it is since we don’t know if it’s had a transmission problem or not yet.

  2. Francisco Saavedra
    October 24, 2023 Reply

    I have a 2014 model Forester. At just 5,000 miles it was totaled and stored in a garage for nine years. After I fixed it, it now has roughly 18,000 miles on it. I want to know if it’s wise to replace the CVT fluid. It appears to function properly, but produces a noticeable humming noise. PLease advice, Thank you!

  3. George Norkus
    October 24, 2023 Reply

    Unless you’re considering the entire cvt fluid as “oil”, remember the the oil does not wear out. It could get dirty and not work very effective but it does not truly wear out. The additives are to blame for wearing out.

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