How to Check Your Transmission Fluid & Why It’s Important

How to Check Your Transmission Fluid & Why It’s Important

Transmission fluid is important because it’s one of the things that keep your car running smoothly. Thus, it’s essential to check transmission fluid levels regularly. 

But you don’t need to rely on your car’s mechanic to take care of the maintenance. You can help keep your car in its best condition by understanding the what, why, and how of checking transmission fluid. In the long run, regular maintenance helps maximise the lifespan of your vehicle. 

The transmission fluid cools and lubricates your transmission, allowing you to shift gears smoothly and run your car with ease. Regularly checking its level and condition will prevent your vehicle from roaring, chattering, or leaking. It also helps avoid a transmission replacement.

Now, that might sound like a lot to take in, but it’s important to understand your transmission fluid so you can check it yourself between car service and repair appointments. So let us break down the what, why, and how of your vehicle’s transmission fluid.

What Is Transmission Fluid and What Does It Do?

The transmission fluid in your car lubricates your transmission gears and keeps your transmission cool. A manual gearbox prevents the bearings from grinding and wearing each other down. In an automatic transmission, the fluid makes the internal parts work by creating friction and hydraulic pressure.

Now, what does that mean exactly?

The transmission, which is the stick you use to drive forward, reverse, and park, always moves when you’re driving. When you shift, some gears move so that you can go forward, reverse, or accelerate. Because there are many gears and internal mechanisms connected to the transmission, the transmission fluid’s job is to keep things smooth.

Now, there are two basic types of transmission fluidsmanual and automatic—but newer transmission fluids have also been created with the advancements in automotive technology. There are synthetic transmission fluids and specialty fluids specified for the transmission type of your car, such as continuously variable transmissions (CVT) and dual-clutch transmissions. 

Let’s go over manual, automatic, and synthetic.

  • Manual Transmission Fluid, also known as manual transmission oil or lube, is commonly found in old manual transmission cars.
    You’ll usually see the oil grade written as 75W to 140W, which means high viscosity or thickness. (Higher number means a higher viscosity.) This high viscosity results in better protection from wear and tear, and corrosion. They also require longer change intervals because they cover the moving parts better.
  • Automatic Transmission Fluid is commonly found in automatic and manual transmission cars. (So, depending on your car’s make and model, the kind of transmission fluid changes. Make sure you check your manual.)
    You’ll usually see much lower oil grades, like 0W or 10W, because the gear system is much more delicate. This lower viscosity allows the fluid to flow freely so power can be transmitted from the engine to the transmission. This means that the fluid also functions in torque converter operation, valve body operation, clutch fiction operation, and brake band friction.
  • Synthetic Transmission Fluid was created to deal with the issues of traditional transmission fluid, which easily oxidises, thins out at high temperatures, and breaks down. They usually come in different oil grades.

Why Should I Check My Transmission Fluid?

You should check your transmission fluid because it is required to keep your car running smoothly. If you don’t check your transmission fluid, you will likely find yourself unable to move forward or backwards. In the long run, not checking your transmission fluid will result in high costs for repair and maintenance.

But what are you checking for? Two things that should alert you are low transmission fluid and debris inside it.

If you’re low on transmission fluid, you may experience problems with shifting gears and some gear slippage, which manifests in a sluggish drive. Your gears may be difficult to engage or shift or, worse, slip to another gear and cause your vehicle to jump suddenly. 

And if your car runs out of transmission fluid entirely, you won’t be able to move. This means expensive repairs. (In fact, replacing a car’s transmission is known as one of the most costly car repairs an owner can prevent.)

Similar things can happen if you have dirty transmission fluid. Your vehicle won’t perform optimally. When sludge or dirt develops, it can result in gear slippage, gear chipping, high friction, or high heat in your transmission. Ultimately, you’re looking at an accident (the gears will slip, or your vehicle will suddenly jump or surge) or high repair and maintenance costs. 

Knowing how to check your transmission fluid level is a lot like knowing how to check car coolant levels; it’s a simple thing to learn and is part of responsible car ownership. 

How Do I Know If My Transmission Fluid Is Low?

Signs of low transmission fluid include: 

  • There are puddles or spots of reddish fluid under your parked car. Now, you’re looking for a reddish colour; black spots of fluid mean a leaking engine oil (which you also need to be worried about) and watery spots mean condensation from the air conditioning (which is not alarming).
  • There is difficulty in shifting. You may hear grinding when you shift gears, or there may be delays, slipping, or sliding when you shift gears. You’ll notice this more when you go around corners.
  • There are odd sounds—roaring, whining, or buzzing—when you accelerate or turn.
  • There is chattering or surge upon take-off. This may feel like your car is jumping, hitting humps, or driving on rumble strips.
  • There is a sweet or tart burning smell. Now, this is already alarming because your transmission might be near empty. Remember that the fluid lubricates your transmission and cools it, so when the transmission fluid is very low, it’s a problem.
  • There is a warning light for high transmission temperature. This is common in newer cars.
  • When you check, the colour of the transmission fluid is muddy or dark brown. The colour of most transmission fluids is red, light, and clear. When it becomes muddy or darker, there may be gear debris, or it has experienced high friction too many times.

How to Check Transmission Fluid

Depending on your car’s make and model, there are two ways to check your transmission fluid: with or without a dipstick. Your vehicle also needs to be parked on level ground. Whether the engine needs to be running depends on the make and model, so consult your car’s manual.

Where Is the Transmission Fluid Located?

The dipstick to check transmission fluid is usually found at the front of the engine, near the transaxle fluid dipstick. However, for some cars, like rear-wheel drives, the dipstick is often found at the rear of the bay. Every car is different, so consult your manual if you cannot find your transmission fluid.

However, it’s more difficult for cars that don’t use a dipstick. Commonly, rear-wheel drives have the transmission fluid towards the back of the engine bay, and front-wheel drives have the transmission fluid towards the front of the engine bay. You will see the transmission fluid usually at the bottom (that’s why you use a long dipstick to check or a long funnel to refill).

How to Check Transmission Fluid With a Dipstick

To check your transmission fluid levels with a dipstick, follow these steps: 

  1. Pull the dipstick out and wipe it clean.
  2. Dip the stick to check the transmission fluid level and condition. To check the level, look at the markings on the dipstick; it should reach the “full” marker.
  3. To check the transmission fluid condition, carefully rub the fluid between your fingers. It should be clean from debris and clear and pinkish. It also shouldn’t smell burnt.
  4. Wipe the dipstick clean and insert it back into its place.

How to Check Transmission Fluid Without a Dipstick

To check your transmission fluid without a dipstick, follow these steps: 

  1. Lift your car on all fours using jack stands. Make sure that your car is level.
  2. Another person should be able to step on the break and cycle the transmission through the gears. After that, leave the car to idle.
  3. Locate the fill plug on the side of the transmission case. Then, carefully remove the fill plug. Fluid should be coming out to indicate that the transmission fluid is not low or empty.
  4. Replace the fill plug.

Checking Transmission Fluid FAQs

Do You Check Transmission Fluid With the Car Running?

Most cars require checking your transmission fluid with the engine running, parked or in neutral, and warmed up. However, some automatic transmission cars (like Honda-manufactured cars) require checking your transmission fluid with the engine off. So, it’s best to check your manual if you are unsure. 

Should I Check Transmission Fluid When Hot or Cold?

Most cars require the engine to be running and warmed up before checking your transmission fluid. The transmission needs to expand to get an accurate reading, which can be achieved through heat. However, some vehicles do require the engine to be turned off (like some Honda cars). 

Do You Check Transmission Fluid in Park or Neutral?

Yes, you should always check your transmission fluid in park or neutral. Make sure your car is parked on a level surface, as any slope may affect the transmission fluid level. This is especially important when using a dipstick. You don’t want inaccurate readings because your car is moving or is parked on a slope.

Will the Check Engine Light Come On for Low Transmission Fluid?

Yes, the check engine light may turn on if your transmission fluid is low. However, there are many other reasons for it to come on, such as a loose gas cap, faulty mass air flow sensor, and low tyre pressure. It’s best to manually check your transmission fluid instead of relying on the check engine light.

How Often Should I Check My Transmission Fluid? 

You should ideally check your transmission fluid once a month. Because the process is quick and easy, it won’t take much time to ensure you have enough transmission fluid. Many people also put checking transmission on their regular car maintenance checklist.

Transmission Fluid FAQs

What Is the Difference Between Normal Oil and Transmission Fluid?

Normal oil, or motor oil, is for your engine, while transmission fluid is for your transmission. Engine oil is for the engine’s performance and fuel efficiency, while transmission fluid is for the car’s hydraulic parts and transmission.

How Often Should Transmission Fluid Be Changed?

Most cars need their transmission fluid changed every two years, or every 50,000 km. For manual transmission cars, it’s anywhere from 50,000 to 90,000 km. However, cars under intense use are recommended to change their transmission fluid every 25,000 km.

However, changing your transmission fluid depends on your car model, make, and even driving style. 

How Much Transmission Fluid Do I Need?

On average, cars will need 3.8 to 16 litres of transmission fluid. For manual transmission cars, it’s usually in the low end of that range. For luxury cars and pickup trucks, it’s generally higher. That said, checking your car’s manual is still best to avoid overfilling.

What Should I Do if There Is a Transmission Leak?

If there is a transmission fluid leak in your car, check the level and condition of your transmission fluid first. The leak may mean your fluid is low and doesn’t necessarily need replacement. Then, consult with your car’s service staff. 

They may recommend refilling, resealing, or flushing. The worst-case scenario is if your reservoir is severely damaged, you’ll need transmission replacement.


This article is published in good faith and for general informational purposes only. Shift Automotive does not make any warranties about the ongoing completeness and reliability of this information, and specifics will vary according to your vehicle’s manufacturer and model. This article is not intended to replace consultation with a qualified automotive service technician.