When you’re running low on transmission fluid, your vehicle cannot function the way it’s supposed to. This is because transmission fluid lubricates the surfaces and components of the transmission system to reduce friction and prevent them from wearing out.
Transmission fluid is supposed to remain in your vehicle for its entire lifespan without changing it, although many mechanics will tell you (sometimes untruthfully) that you should change this fluid every 50,000 miles no matter what. Sometimes frequent flushes of the transmission fluid are recommended as well.
Like oil, when your transmission fluid is low or bad, it can cause serious problems to your car’s transmission. Here are some common symptoms of low transmission fluid. If you don’t top off or change your fluid, you may have an expensive repair to deal with in the future.
Common Low Transmission Fluid Symptoms
You’ll find that pretty much all signs of low transmission fluid point to a transmission fluid leak as the cause. If any of the following symptoms show up, the first thing you should do is check the transmission fluid level to confirm.
While you’re at it, check the condition of the fluid. New transmission fluid should appear red and almost transparent. If the color is brown or darker, you may have internal problems. See our transmission fluid color chart to see what the color of your fluid says about its condition.
#1 – Transmission Fluid on Garage Floor or Driveway
This sign that you’re running low on transmission fluid is pretty obvious but often overlooked. When you notice a small puddle or spots of a red or brown fluid underneath your vehicle where your engine and transmission sit, you likely have a transmission leak.
This is usually due to a failed seal or gasket, loose drain plug, or even damage to the transmission pan itself.
Some leaks are incredibly minor, and while you eventually want to fix them, keeping an eye on your transmission fluid level and topping off when needed will get you by. But for most leaks, you want to take care of the issue right away.
#2 – Slow Gear Engagement
With low transmission fluid in your vehicle, you will have a temporary delay after you move the gear lever into reverse or drive. The reason being is that the gear shift cannot take place immediately if there isn’t enough transmission fluid pressure.
With low fluid, it make take up to 2 or 3 seconds to build enough pressure for the gear change. This same symptom will appear if there’s a problem with your transmission valve body so if you confirm the ATF level is fine, that’s another possible cause.
#3 – Trouble Shifting Gears
Manual and automatic transmission vehicles both must have transmission fluid that is clean and able to flow freely inside of your transmission. If your transmission fluid is contaminated by dirt or other material, then its response will be very laggy and sluggish.
Once that starts happening, your gear shifting will cause the gears to change too fast or too slow as you’re driving the vehicle. If you are driving a car with a manual transmission, it could be very difficult for regular gear shifts and you may not even be able to get into certain gears at all.
#4 – Strange Noises While in Gear
A properly operating transmission should be silent to the driver. But if you start hearing rattling noises or a rhythmic pounding while in gear and not when in park or neutral, you may have an issue with your torque converter due to the car being low on transmission fluid.
If you hear grinding or clattering while changing gears, it may be another sign that not enough transmission fluid is in the system.
#5 – Transmission Overheats
Similar to how a motor needs the proper amount of engine oil to lubricate all parts and maintain correct operating temperature, the transmission needs an adequate level of transmission fluid to keep it at the proper operating temperature.
With not enough transmission fluid, your transmission will quickly begin to overheat due to excess friction between moving parts. You may notice a strong smell from the burnt transmission fluid or even smoke coming from the area of the transmission.
If you notice either of these while driving, pull your car off the road immediately and let everything cool down for a while. If the temperatures get too high, then you may have serious internal damage and may need a complete transmission rebuild.
#6 – Transmission Gear Slippage
Low transmission fluid could reduce the hydraulic pressure in the system. If you don’t have enough hydraulic pressure, you won’t be able to remain in the current gear that you have selected.
A gear slipping presents itself by the engine jumping to a higher RPM while driving yet the car is not moving any faster. This is often an indicator that significant damage has already occurred to the gear teeth.