Why and when to change your vehicle’s transmission fluid

By June 19, 2017Maintenance

Why and when to change your vehicle’s transmission fluid

We’ve all heard of oil changes for our engines, but what’s up with transmission fluid changes? The transmission is a key component of the car, where all the gears change to get the car moving forwards and backward; and where there’s movement—there’s friction. It makes sense that there’s some sort of fluid required in there to keep things cool and lubricated. But there’s not a one-size-fits-all fluid for all transmission types! Automatic and manual transmissions require different kinds of fluid. 

These are the most common ones.

Transmission fluid: Type F

Used for: Cars from the 1970s. If you’re sporting a Pontiac Firebird, then you’ll need to nurture that tranny with a Type F transmission fluid. The one differentiator of the Type F fluid is that it did not include friction modifiers that are needed in today’s cars to reduce friction in lubricated parts.


Used for: The most common cars on the road today. DEXRON and Mercon are the most popular fluids today, and have friction modifiers and come in various different grades.

HFM transmission fluid

Used for: Cars manufactured by Honda, Jeep, Hyundai, and Toyota. These manufacturers have been known to recommend Highly Friction Modified (HFM) fluids instead of DEXRON/Mercon, so check your owner’s manual!

Synthetic transmission fluid

Good for: Any car you love or plan to keep; that’s because synthetic fluids make your transmission perform better and provide improved resistance to things like heat, cold, oxidation, and friction.

lots of transmission fluid
Bottle shape does not affect the performance of the fluid, no matter what the marketing department says.

Can’t I just fill it up once?

Just like engine oil, transmission fluid protects the various working parts of the transmission from damage. Sans fluid and things can go south fast. Gears rub up against each other (in a bad way), debris and particles start to collect, affected the ability of the transmission to shift gears and accelerate.  If things are left unkempt, a transmission rebuild that costs anywhere from $3,000 – $5,000 can be on the horizon.

Changing and maintaining a healthy amount of transmission fluid in the gearbox not only helps soothe one’s bank account; it also provides some great additional benefits. Getting a transmission fluid change:

  • Cleans and protects the transmission’s metal surfaces
  • Conditions gaskets
  • Cools and reduces the high operating temperatures of the transmission
  • Increases rotational speed

    Is it complicated or expensive?

    Changing transmission fluid can be (over)simplified into a four-step process:

    1) Turn car on and get it to operating temperature, 2) Drain the existing transmission fluid, 3) Examine the pan and most likely replace the gasket and filter, 4) Add the new transmission fluid.

    Depending on what type of fluid you use (Dexron/Mercon vs. synthetic) and where you bring your vehicle for this service (a local shop compared to a dealership), the cost can vary.

    With RepairMatch, you can get a transmission fluid and filter change on most cars for about $170. We find the most reputable shop that’s closest to you to get the job done.

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