Difficulty Shifting Gears - If you ever accelerate and hear your engine rev, but don't feel your car go any faster, your transmission is likely stuck in gear. Drivers with a manual transmission will feel some resistance when you try to shift. Not being able to shift is a direct result of having low transmission fluid.
If your transmission fluid gets low enough, the check engine light could pop on. It's important to have this checked out to make sure it doesn't result in any serious damage.
On cars without a dipstick, the engine oil level is read via a level sensor (on the bottom of the engine oil pan). Conductive sensors are commonly used to measure engine oil. Conductive level sensors use a low-voltage, current-limited power source applied across separate electrodes.
If your vehicle is equipped with a sealed transmission, it's a safe bet that it's designed to last the lifetime of the vehicle. Even sealing technology has come so far that manufacturers assume leaks to be the exception, rather than the rule. Either way, there's no need for dipsticks to check ATF.
Many modern vehicles use a sealed-for-life transmission that never requires checking or fluid replacement—so they don't have a dipstick. (Refer to your owner's manual for your model's specific service schedule and to double-check whether it has a transmission dipstick.)
Automatic transmissions that shift hard, jerk or shake during a shift change may mean your transmission fluid needs changed or fluid level is low. In manual transmission vehicles, abnormal gear shifts could indicate damaged gear synchros, worn clutches or other, more severe issues.
You can add more by inserting a funnel into the tube the dipstick was withdrawn from and pouring a small amount of automatic transmission fluid into the pipe. Check the level each time you add a little until the level is right between the two lines.
If you're like many drivers, you often forget to check the fluid levels in your vehicle, and if the fluid level in your transmission is too low, you will notice a gurgling noise. This noise is caused by the excess air in your transmission line.
If you hear a sound you've never heard your car make before, take it to your local shop immediately. If the sound resembles humming, buzzing, or clunking, you may be experiencing transmission failure.
How long can a car run without transmission fluid is up to about 10 miles on low to no transmission fluid, but doing so would be extremely risky. Transmission fluid is essential for helping your car shift gears smoothly. Without it, gears are exposed to added friction and may not be able to move at all.
In an automatic vehicle, the transmission fluid provides a coupling between the engine's output and the gears in your transmission. If there is no fluid, there is no hold, the gears cannot spin and therefore the car won't be able to move.
Transmission fluid expands in heat and in order to receive accurate results, it must be under normal operating conditions. If the fluid is checked when the engine is cold, you may get false results indicating the fluid is low. Allow the engine to continue running while you check the level.
The most likely reason that a car jerks when accelerating from stop is a problem with the clutch. It could be due to worn-out friction material or a pressure plate defect (or combination of both). It could also be caused by an oil leak contaminating the clutch plate.
The most common reason for a car jerk while accelerating is that one or more of your spark plugs may be going bad, which will lessen performance if the problem persists. If you think this might be the case, have a professional check them and replace them if necessary.
If you are experiencing difficulty accelerating, gear engagement hesitation, power loss, or noise with your vehicle, you may have a slipping transmission. If your vehicle's transmission seems to be slipping, it can be a warning sign of failure to come.
Also, some automatic transmissions do not have dipsticks or may require that a service professional inspect the automatic transmission fluid level. Check the vehicle's owner's or service manual.
While you can add fluid when it gets low, many car manufacturers recommend a transmission fluid change every 30,000 to 100,000 miles (48,000 to 161,000 km) depending on the make and model of your car.
Many modern cars don't have a transmission fluid dipstick, and automakers instead recommend a service center check the fluid level because it's often done from underneath the car.
Why did auto manufacturers stop putting dipsticks on cars to check automatic transmission fluid levels? CVTs are becoming increasingly common, which can be destroyed very quickly if the wrong fluid is used, so they don't want the owner touching that.
Transmission Warning Light
If this warning light turns on, you should immediately stop your vehicle and turn it off when it's safe to do so. Your transmission could be overheating when there are low transmission fluid levels, worn internal components, and several other reasons.