How Often Should I Change Transmission Fluid?


It depends on your vehicle and driving habits.

That’s a cop-out. But, it’s true.

Automatic-transmission-fluid-change recommendations vary from one original equipment manufacturer (OEM) to another. Plus, if your driving habits are like most motorists and fall under the “severe” designation (towing, hauling, daily short trips less than 10 miles, etc.), many OEMs recommend changing transmission fluid more frequently.

Check your owner’s manual
Start by looking in your vehicle owner’s manual. It’ll provide maintenance recommendations, typically in a table in the back.

The 2017 Ford F-150, for example, requires automatic transmission fluid changes every 150,000 miles in normal service, 30,000 miles if you tow and haul. My wife’s Honda CR-V calls for transmission fluid changes every 90,000 miles in normal service, 30,000 miles in severe service. Some transmissions are considered “fill-for-life”.

These differences illustrate the importance of digging your owner’s manual out from under the napkins and broken sunglasses in your glove box and checking for yourself.

Go by the book, but when you don’t…
But, really, how many of us dutifully follow the recommendations in our owner’s manuals down to the mile? True, some of us look forward to working in the garage on the weekend. But most motorists don’t have the time, which means fluid-change recommendations morph into loose suggestions, something you fit into your schedule “sometime before winter, maybe.”

But soon you’re loading down the Family Truckster for the first summer trip to the beach, yet the tranny fluid still hasn’t been changed.

Not good, especially if you tow or haul.

Heat kills transmissions
Over time, transmission fluid oxidizes (chemically breaks down). High heat generated from towing and hauling speeds the process. Fluid that has broken down can cause sludge and varnish to form, which clogs narrow oil passages and contributes to clutch glazing. Soon, your vehicle can begin to shift hard, jerk or hesitate.

In these cases, wouldn’t it be great to use a transmission fluid formulated with reserve protection against heat in case life gets in the way of recommended maintenance?

AMSOIL Signature Series Synthetic Automatic Transmission Fluid’s built-in reserve protection means it lasts for twice the OEM’s severe-service drain interval. That means you can rest assured your transmission is protected, even if service is delayed.

In fact, after 180,000 miles in taxi cabs driven in the searing Las Vegas heat, Signature Series retained 83 percent of its oxidation inhibitors, proving its long-lasting resistance to thermal breakdown. Plus, the used fluid with 180,000 severe-service miles on it still met the Chrysler ATF+4 standard’s new fluid requirement for resistance to thermal breakdown.

AMSOIL also offers OE Synthetic Transmission Fluid, which provides excellent protection for OEM-recommended service intervals for those of us who don’t require the reserve protection of Signature Series.

Fill for life?
I should mention “fill-for-life” transmissions, which are becoming more common as OEMs continue to look for ways to simplify (dumb-down) vehicle maintenance. Most don’t even have a dipstick for checking fluid. On those that do, they can be located in hard-to-access areas. In these cases, check a service manual for dipstick location and instructions for checking the fluid. Although the transmission is designed to be “filled for life,” that typically means fill for the life of the warranty. It’s just as important to service these units and replace the fluid once in a while to ensure the transmission lasts as designed and gives you years of solid performance beyond the OEM’s warranty period.

How Much Transmission Fluid to use

Related Posts


  1. Thanks for pointing out the reasons due to which transmission fluid loses its ability of lubrication. Transmission fluid plays a vital role in the performance of the transmission by providing a friction less surrounding to various components of the vehicle. However, transmission fluid loses its ability of lubrication over time due to above-mentioned factors. Use of burned transmission fluid could bring the vehicle to a halt. So, the condition of the transmission fluid should be inspected regularly and if necessary replace such lubricant after certain time interval as recommended in the owners manual.

  2. I was wondering if I can safely mix factory AT4 and Amsoil synthetic transmission fluid? Since the drain and filter change keeps about 50% of the original fluid in the tranny.

  3. Hi John,

    I have a 2001 Honda Odyssey with 237,000 miles and original transmission. It has developed a delayed shift from 1-2 and sometimes a quick shift to 3rd. The fluid was changed in December 2016 with Honda fluid. Any thoughts or suggestions to extend the life of the transmission and/or improve its performance?

    1. Hi Jason,

      237K is getting up there. We wrote a post about common fixes for a transmission that jerks or hesitates. In essence, start by checking the fluid level. It could be low. Other possibilities include worn out fluid that has lost its frictional properties and fluid with poor cold-flow properties (which likely isn’t the problem if it’s happening in May).

      I hate to be the bearer of bad news, but the tranny may just be wearing out. Like I said, 237,000 miles is a lot, especially if your haul or pull a trailer once in a while.

      If it were my vehicle, I’d start by checking the fluid. Ensure it’s not low and examine its condition. If it’s black and appears burned, try changing it before visiting the dealership. In my experience, going to the dealership with a faulty tranny is just asking for a $2,500-plus estimate to fix it. Start with the cheap fixes first!

      Thanks for reading,


  4. Hi! I own a 2006 Toyota Corolla CE which comes from my Dad who can’t drive anymore because of his old age. An excellent car which I think that it will last again for sevral years if I take good care of it by following the maintenance schedule.
    Only one thing, as the transmission fluid has never never been changed, I’m thinking of changing it very soon. So what I like to know, is Amsoil synthetic automatic transmission fluid better than the one which is sold at a Toyota dealer? I’m asking you that because whenever I can I’ve always bought the best oils and fluides for my cars in order for them to last the longest time possible and also avoid the most possible car problems weather in my driveway or when on a street or highway.

    So, knowing that I’ll be hearing of you very soon, I would like to Thank you very much in advance for your information. Have a good day!

    YVES LAVOIE from Drummondville Québec Canada

    1. Hi Yves,

      Thanks for your interest in AMSOIL. I have a Corolla myself, and it’s a great little car.

      While we don’t have test results showing the performance of AMSOIL synthetic automatic transmission fluid compared to Toyota’s OEM-branded fluid, we have something better, in my opinion – results of severe-service testing we performed in a fleet of Las Vegas taxi cabs. After more than 180,000 miles of severe driving in the scorching desert heat of Las Vegas, AMSOIL Signature Series Synthetic Automatic Transmission Fluid guarded against wear and damaging sludge and delivered flawless performance. Click the link above to view the images of the transmission teardown and see for yourself.

      If the fluid performed that well in Las Vegas taxi cabs, think of how great it will perform in your Corolla.

      Thanks for reading.

  5. I did not realize that most cars do not even have a dipstick for checking transmission fluid. It is also good to realize that sometimes transmission fluid is in a hard to access area. Regular maintenance visits would be a good thing to do for your car. A mechanic could help you solve small problems before they become larger issues.

  6. I have a 2014 Tacoma 4×4 auto with 25,000 miles on the clock. It’s my first automatic (always had manuals previously which I changed out at 25,000 religiously). My dealer shop foreman keeps refusing to service it. It’s one of those with no dipstick or way to examine the fluid. He keeps telling me that Toyota vacuum seals their traines and that it would be a waste of money. It has not towed during it’s life, but does have a high volume of short trips. I’ve trusted all my vehicles, including motorcycles, for years with Amsoil with very good results. I’m hoping you can give me some good info pertaining to what is the best way to proceed with my Taco?

    1. Hi Allen,

      Your transmission contains a drain plug and a fill plug, similar to a differential, so it is possible to change the fluid. It can be a tricky process, though, so we recommend visiting a professional. The bottom line, though, is it can be done. Just visit a different dealership or an independent transmission shop.

      Thanks for reading.

Leave a Reply