If some transmission fluid is good, it follows that more would be better, right? Not true when it comes to transmission fluid. You don’t want too much fluid, nor do you want too little.
How do you know if there is too much transmission fluid in the system, and how does that differ from a system with low transmission fluid? We will discuss everything you need to know here.
How Much Transmission Fluid Does a Car Hold?
The amount of transmission fluid your vehicle uses depends on the vehicle! Most cars take 4 to 10 quarts of transmission fluid, but some passenger vehicles take as much as 17 quarts!
Because of this, you must know how to find out how much transmission fluid you need.
First, you can check your owner’s manual. This will tell you exactly how much oil your transmission takes, and it will tell you the type of fluid to use.
If you no longer have your owner’s manual, you can contact the local dealership or Google to get this information. Just be careful to get your information from a trusted source if using Google.
How Much Transmission Fluid is Too Much?
Technically, any amount of transmission fluid above the maximum level on the dipstick is overfilling. The level of overfilling can differ in terms of the vehicle and the type of transmission.
Many think “too much” is 1 quart or more over full, however, it’s all relative to the vehicle’s transmission fluid capacity.
One extra quart of transmission fluid in a car that takes 5 quarts is more serious than the same quart overfilled in a truck that holds 15 quarts.
So why would someone overfill a transmission?
Most of the time when this happens, it’s a mistake. They may not have drained all of the old transmission fluid or believed the tank is bigger than it is.
Another common mistake is checking the vehicle’s transmission fluid when it is cold and not hot. Transmission fluid expands when it is hot, and the only procedure for checking your vehicle’s transmission fluid is when the engine is at operating temperature.
Signs You’ve Overfilled Transmission Fluid
You’re here because you think you’ve overfilled your transmission fluid, so here are some of the signs or symptoms you will see if you have an overfilled transmission.
Keep in mind, these are signs you have an overfilled transmission, but some of the symptoms could also signal other issues!
#1. High Fluid Level on Dipstick.
Your transmission has a dipstick for a reason, so if you’re looking to determine if there’s too much transmission fluid, it’s the first place to check.
You should note that you need to check the transmission fluid at operating temperature to accurately check it on the dipstick.
Of course, if you cannot get your vehicle to full operating temperature for some reason, you can still take a look at the dipstick to get an idea.
You should check the transmission fluid when hot because as the fluid is heated, it expands. This means if you check it cold and it’s already high, it will only get worse as you check it at operating temperature.
#2. Trouble Shifting Gears.
Transmission fluid is intended to keep everything lubricated and shifting smoothly. While having the correct amount of transmission fluid shouldn’t create any issues, having too much could lead to a premium for space in the system.
In automatic transmission vehicles, you’ll experience “harder” shifts, and in a manual, you’ll find you have to apply a little more force to get to the gear you want.
Either way, shifting won’t be as easy as it should be (it may not even shift at all), plus you are wearing out all of the other parts that go into the process.
#3 Engine Overheating.
One of the purposes of transmission fluid is to prevent the system from overheating, so it might seem odd that too much could cause it to overheat.
Normal transmission temperatures fall somewhere between 170-225 degrees. Let’s think about that for a second. Too much fluid can cause the temperature to go above that.
However, when there is an excessive amount of transmission fluid in the system, it is simply not able to work as it is designed. It will not be able to cool things off properly and will cause your transmission to overheat because of too much fluid in the system!
#4 Leaking Fluid.
So, when you have too much transmission fluid, it creates too much pressure, and seals can only handle so much. When this happens, some of the seals can crack or fail, and you’ll notice some transmission leaking as a result.
While this will slowly bring your transmission fluid back to the proper level, it will not stop there. Instead of having too much transmission fluid, you won’t have enough fluid sometime soon. If you have a leaking seal, you’ll have to drain the entire system and replace the seal to fix the issue.
#5. Odd Noises.
Whenever anything in your vehicle begins to not work as it should, it typically begins to make some noise. While an overfilled transmission isn’t likely to make the most obnoxious noises, you should be able to hear something out of place.
It could be a whirring, grinding, whining, or humming noise. If you hear any of those noises coming from your transmission, something is going on, and you will have to figure out what it is.
#6. Slipping Transmission.
Many people ask, Will too much transmission fluid make it slip? The answer is yes. If you have overfilled your fluid, you are putting extra pressure on everything in your transmission.
This can have a wide array of effects, but one that is very likely is that it will randomly at times, randomly push your transmission out of gear.
This is known as “slipping.” All you will notice in an automatic vehicle is a very brief moment of a loss of power and a little clunkiness while you drive.
If you drive a manual transmission vehicle, you will be out of gear, and you will have to get back in gear.
When this happens, you will often hear a grinding noise as well. If you have a slipping transmission, you will have to figure out why it is slipping, and there is definitely a chance it is due to too much transmission fluid.
You may also be experiencing slipping if you drive a high-mileage vehicle and recently had the transmission fluid flushed.
#7. Part Pitting.
This is really the worst-case scenario, but if you leave an excessive amount of transmission fluid in the system for longer than it should be, you can create part pitting. This can occur on various components in your transmission, including the rollers and gears.
Ultimately, the part pitting will lead to either transmission failure, meaning you will either rebuild or replace the transmission.
Can Too Much Transmission Fluid Cause Damage?
It is definitely possible to damage your car by overfilling it with transmission fluid. When added to higher amounts of fluid, transmission components can experience compromised performance and subsequently damage their internal components.
Now, don’t think we are talking about a few excess drops of transmission fluid, but if you overfilled the transmission fluid reservoir by 1 quart or more, some issues can arise. For instance, due to the added pressure from having too much fluid, seals can wear out quicker, and you could develop leaking transmission fluid.
Also, having too much transmission fluid can lead to engine overheating, and when that happens, components can become damaged. Lastly, the damages due to excess transmission fluid will include part pitting, which, when that occurs, reduces the lifespan and potentially damages various internal components.
How to Remove Excess Transmission Fluid
If you are a victim of too much transmission fluid, you are between a rock and a hard place because the only way to drain the excess fluid is through the drain plug.
Since you have to drain the fluid through the drain plug, the hard part comes in because to salvage whatever fluid you can, you need to put the drain plug back in while the fluid is flowing out.
And because this is the only way to check your transmission fluid level, the transmission fluid will be at operating temperature, which is hot.
While you can try to siphon off transmission fluid through the dipstick tube, it will take a while, and you will need a special tool to siphon the fluid off Especially if you have a lot of fluid to drain, you need to drain the excess through the drain plug.