Updated at: 06-08-2023 - By: Lucas

It was easy to find a handbook that showed you how to change the transmission fluid, but it failed to mention the dangers, and now your gearbox is overflowing with fluid.

VehicleFreak does not feature many transmission-related articles because I’ve seen this problem all too often. Taking the vehicle to a repair comes at a price that considerably outweighs the hazards.

Even if you can’t afford a repair, you should still be a conscientious owner, in my opinion. How to drain or siphon the surplus fluid is what I’ll be explaining in this post.

How To Measure Transmission Fluid Levels

Overfilled Transmission Fluid

Inaccurate measurement is the primary cause of transmission overfilling mishaps. Transmission maintenance is more difficult since it is less forgiving and more delicate than engine oil changes.

To get an accurate reading of the fluid level, you need to drive for around 15 to 20 minutes and keep the engine running while you remove the dipstick from the transmission.. This manner, you’ll be able to get an accurate reading and determine whether or not the transmission has sufficient fluid.

How To Extract Excess Transmission Fluid

Overfilled Transmission Fluid-3

Excess transmission fluid can be removed in two methods.

There are two ways to remove the water: one from below, and the other from above.

You can drain the fluid by unscrewing the drain cap for free, but it takes time to prepare and you’re practically certain to overdo it.

From above, you’ll have more control over the amount of fluid you drain, but a siphon pump or your own will be necessary.

The Drain Plug Method

It’s not ideal, but if you’re quick, you can remove the extra fluid by loosening the drain stopper. Without access to a mechanical trench or a lift, you’ll need to utilize a car jack and car stands to raise the vehicle’s underneath.

You’ll need a variety of tools to get the job done.

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Detailed, step-by-step guidance

  • Let the vehicle cool completely before you begin. 
  • Raise the vehicle behind the front left wheel, and place the first stand underneath a reinforced area.
  • Repeat the process on the other side, then place the wheel stops behind the rear wheels.
  • Put on a pair of disposable gloves.
  • Use the socket to loosen the drain plug. 
  • Position the drain pan underneath, then continue to unscrew the plug until you can do it by hand.
  • You’ll have to keep the plug in your hand once the fluid starts to drain, so you can quickly seal the hole. It’s important that the transmission is cold, otherwise, you might burn your hands.
  • Seal the drain plug tight, and lower the vehicle.
  • Drive it for 15-20 minutes to heat up the transmission fluid, then check the levels again

However, you don’t know exactly how much fluid you need to expel using this procedure. Try to find out whether anyone has found a correlation between dipstick readings and the amount of fluid in your vehicle.

To avoid repeating the tiresome and time-consuming procedure of bringing the vehicle back up, make sure you let out adequate oil. This can lead to overfilling again if you let out more than you need to.

Despite the fact that I’ve included this method in this guide, I strongly recommend siphoning liquids from the top. You’ll learn how in the following section.

The Siphoning Method

Using a cheap fluid transfer pump makes it much easier to remove the extra fluid. A rubber hose and a large syringe can also be used to build a pump.

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Detailed, step-by-step guidance

  • Prepare a container large enough to contain the pump and the hose so it remains clean during the process. 
  • Let the transmission and the engine cool off, then insert the hose into the dipstick hole. 
  • Pull out the transmission fluid with the pump handle. 
  • Start the engine and drive for 15-20 minutes to heat up the transmission, then check the levels. 
  • Repeat the process if necessary to get to the ideal fluid level.

If you don’t know how much fluid to remove, this procedure is more convenient and can be performed in a shorter amount of time.

On the pump, you can establish a set of gauges that tell you the amount of water that’s remaining in the hose and canister. Measure the distance between the maximum fluid level and the current resting point.

A correlation between the fluid level and amount extracted can be established after the initial draw, and adjustments can be made accordingly.

The Symptoms of Overfilled Transmission

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It’s always a good idea to familiarize yourself with all of the symptoms so that you can identify them more quickly in the future if your transmission is overfilled. That you recently replaced the fluid is, of course, a clear indicator.

Problems With Gear Changes

The transmission will become difficult to shift gears if there is too much oil in it. When shifting gears, you’ll notice delays, or your transmission will go into “safe mode.”

Transmission Noises

Wailing and humming noises from the transmission are often heard when shifting gears. As the RPM grows, so does the volume and pitch of the noise.

Oil Leaks

The transmitter is a completely sealed unit, meaning that nothing can enter or exit it. Adding too much fluid might cause gaskets to break and leak transmission fluid if you do it incorrectly.

Transmission Overheating

When the transmission overheats, the A/T temperature flashes on the dashboard. Despite the fact that it may appear counterintuitive, as the pressure develops and leaks develop, the volume of fluid will fall below what is required to adequately lubricate the gears.

Seek Help From A Professional

If you can’t fix the problem yourself, don’t hesitate to take your car to a mechanic. To choose the most affordable mechanic, start by asking around and explaining your circumstance.

It costs up to $100 in labor for a complete fluid change; however, if the fluid level is only supposed to be corrected, the cost should be much lower.


Can too much transmission fluid cause the transmission to slip?

Overfilling the transmission can cause gears to slip, as well as other issues like noise, shifting difficulties, and overheating.

Does it hurt to overfill transmission fluid?

The transmission fluid is no exception to this rule. There are a variety of issues that might occur if you add too much, including transmission wear and tear.

How many quarts are in a transmission?

Between 9 and 13 liters of fluid can be used in a transmission, depending on the model.


This might cause major harm to the transmission if it isn’t taken care of early enough. Doing it yourself can save you money and most importantly, preserve your transmission in maximum condition, so it may take an hour or two to get the fluid level just right.