Whether you drive a lot or not, knowing how often to change transmission fluid is critical to your vehicle's long-term survival.
Ideally, you should change the fluid from 30,000 to 60,000 miles in a manual vehicle but 60,000 to 100,000 miles in an automatic.
But since these are just estimates, you should check the fluid recommendations in the owner's manual.
Below, we'll discuss the length of time between transmission fluid changes, the symptoms of low fluid levels, and how to check the fluid.
Removing a transmissions oil pan to change its filter.
How Long Should You Change Transmission Fluid?
It depends on the vehicle!
You should look inside the manufacturer's manual for the recommended timeframe between manual and automatic transmission fluid changes.
Generally speaking, manual transmissions require a fluid change around every 30,000 to 60,000 miles, while automatic transmissions benefit from transmission oil changes between 60,000 and 100,000 miles.
Although, the following factors affect this:
- Make and model
- How often you drive
- Transmission type
- Vehicle age
In short, always defer to the owner's manual.
What Happens if You Don't Change Transmission Fluid?
Regularly changing transmission fluid increases your transmission's longevity.
However, choosing not to change your transmission fluid results in poor lubrication and heat dispersion.
Therefore, your car will experience excessive wear and tear, especially on its clutch and other components.
When the clutch system loses grip, old fluid could be the only factor providing enough friction to ensure clutch engagement and prevent transmission failure.
Low transmission fluid decreases hydraulic pressure, causing gear slippage.
Usually, gear slippage manifests as not being able to accelerate correctly.
You'll likely notice your vehicle running at higher RPMs despite moving slowly.
Trouble conducting gear shifts can also occur in both automatic transmissions and manual transmissions.
Sudden lurches when changing gears are probable too.
None of the above makes for a comfy drive, so taking your car to a service center as soon as you notice these problems is essential.
Otherwise, you risk a costly repair in the near future due to the premature wear on your vehicle.
Draining old transmission oil.
Should You Do a Transmission Flush or Change?
As with an engine oil change, you should take your car to a manufacturer-specific service center to deal with your low transmission fluid issue.
The mechanics at these garages have specialist knowledge of your particular vehicle, ensuring they make the right decision as to whether to conduct a transmission fluid change or flush.
The owner's manual will also tell you whether a flush or change is best.
Remember that a flush is only appropriate if there aren't any signs of damage.
Performing a hydraulic fluid flush with damaged material, you risk destroying the valve body sitting at the bottom of the transmission.
How Do You Know When Your Car Needs Transmission Fluid?
A low transmission fluid level results in:
- poor gear shifting;
- hesitation;
- surging;
- increased transmission temperature;
- inconsistent or jerky shifts;
- odor coming from your transmission;
- rough idling;
- warning lights (specifically, the check engine light); and
- bad acceleration.
That said, the most obvious sign that it's time for a transmission fluid change is leaking.
It might be difficult to tell the difference between leaking transmission fluids and other fluid drips, so you need to consider their colors.
If you see puddles or dark spots under your vehicle, grab a piece of cardboard and place it under your vehicle.
Is the fluid reddish-brown, dark red, or bright red?
If so, your vehicle has a transmission problem.
How to Conduct a Transmission Fluid Check
While your car's manufacturer recommends taking your vehicle to a service center for a transmission fluid level check, you can do it at home if your model comes with an easy-to-reach dipstick.
Check the owner's manual to figure out whether your vehicle fits the bill before following the step-by-step instructions below on how to check the transmission fluid:
- Consult your owner's manual to determine the recommended transmission fluid check procedure.
- Park on a level surface for an accurate reading.
- Consider the engine's cooling fans. They may keep running after you switch the engine off. Most manufacturers recommend the engine and transmission are at operating temperature before you check the transmission fluid level.
- Find out whether you should check the transmission fluid with the engine running by looking at the owner's manual. It varies depending on the make and model.
- Locate the transmission dipstick handle. It's normally a bright color, but the owner's manual will tell you exactly what to look for.
- Gently remove the dipstick, taking care not to spill any liquid on the engine or exhaust components.
- Use a clean rag to wipe the dipstick.
- Reinsert the dipstick and remove it again to check the level. It should fall between the low and full notches.
- Always adhere to the recommended levels if you need to perform a transmission fluid change.
- Finally, reinstall the dipstick.
Can You Change Transmission Fluid Without Changing the Filter?
Whether you have an automatic transmission or a manual one, you can change the transmission fluid without switching the filter.
But if the following applies, you should consider asking a mechanic to fit a filter while they add new fluid:
- Scent — A burning odor indicates a clogged transmission lubricant filter.
- Color — A rusty or dark color could signify a debris-filled filter.
- Noise — An odd sound while shifting gears suggests a bunged filter.
- Clucky gears — While it's more likely to be low transmission fluid that causes this problem, it could be down to a damaged or plugged filter.
Clean transmission oil on dipstick.
Is It a Good Idea to Change Transmission Fluid on High Mileage?
It's risky to change the transmission fluid in a high-mileage vehicle.
While you should change it periodically to ensure adequate hydraulic pressure, if a high-mileage vehicle is running on the same oil from the factory, you should leave it alone.
Sludge can build up inside an automatic transmission, but it can sometimes act as a seal in certain parts of the transmission that will, in turn, maintain hydraulic pressure.
If you go ahead with the transmission fluid change, it could fail without warning due to leaks and loss of fluid pressure.
How Long Does It Take to Change Transmission Fluid?
A qualified mechanic can change manual and automatic transmission fluids in around 30 minutes.
They can do an uncomplicated flush in three or four hours.
Conclusion
Your vehicle may not need hydraulic fluid change until 60,000 miles (sometimes even 100,00!), depending on the transmission type.
However, always check the owner's manual.
Even if you check your levels at home, it's typically best to consult a professional mechanic as they will know whether a flush or change is necessary.