Low Transmission Fluid: Symptoms, Causes, and Repairs
Like your body needs water, your trans needs its fluids.
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The Floor Check™ is a subtle art known and executed by nearly every home mechanic around the globe. What was once a clean garage floor, driveway, or parking spot has now been Jackson Pollacked by a foreign substance. Is it alien blood? Oil? Melted Burt’s Bees? You must inspect closer.
So, you drop down, belly-to-ground like a burpee, to get a closer look. The color, the smell, and the feel of the liquid (no tasting necessary) tell you everything you need to know: It’s transmission fluid.
You can’t use The Floor Check™ method unless you know what you’re looking for, so The Drive is here to educate you on the details and walk you through the process. While we’re at it, we’ll examine common causes of a potential leak and possible solutions to your problems. Let’s get to it.
What Is Transmission Fluid?
In both manual and automatic transmissions, transmission fluid is the liquid that lubricates and cools the device’s internal parts. In an automatic transmission, the system also utilizes the fluid for hydraulic pressure and actuation. In real-world terms, it’s the stuff that keeps your transmission shifting smoothly and on time.
What Color Is Transmission Fluid?
Transmission fluid is typically red or pinkish, but in rare cases, other manufacturers might choose something else. In good condition, the fluid is slightly translucent. If it is bad and/or soiled, it might look dark red, brown, or milky.
What Does Transmission Fluid Smell and Feel Like?
Transmission fluid is viscous and slimy like motor oil. It is relatively odorless, if not a bit chemically, but bad transmission fluid might smell burnt and nasty.
How Long Should Transmission Fluid Last?
For this answer, it’s best to look into the details for your specific car in your owner’s manual as some manufacturers claim lifetime use, while others only 100,000 miles. There are those people who prefer to change transmission fluid every 40,000-50,000 miles, but that can be considered wasteful and excessive if your car is in good working order. Again, check the book.
Because transmissions are extremely complicated mechanisms and transmission oil flushes require a specific machine, we recommend taking your car to a trusted and proven professional.
Causes of Low Transmission Fluid
There is essentially one primary reason your transmission fluid is low, and it’s leakage. The fluid is finding its way out of the system and into our big world. Here are a few places the leak could occur:
- Transmission pan crack or puncture
- Transmission pan gasket failure
- Fluid line crack
- Axle seal failure
- Torque converter failure
Symptoms of Low Transmission Fluid
- Drips or puddles underneath the car
- Difficulty shifting through gears and/or slipping
- Shuddering or shaking
- Lurching or sudden jerks
- Transmission won’t engage
- Humming or clunking noises
- A burning smell
Servicing a Transmission
Know the basics and prepare the necessary tools before you begin your project.
Estimated Time Needed: 20 minutes to 2 hours
Skill Level: Beginner to Professional
Vehicle System: Transmission
Working on your car can be dangerous and messy, so here’s exactly what you’ll need to ensure you don't leave the garage in the same condition in which you entered.
Everything You’ll Need For Servicing a Transmission
We’re not psychic, nor are we snooping through your toolbox or garage, so here’s exactly what you’ll need to get the job done.
Parts List (H3)
- Transmission fluid
- Transmission gasket
Organizing your tools and gear so everything is easily reachable will save precious minutes waiting for your handy-dandy child or four-legged helper to bring you the sandpaper or blowtorch. (You won't need a blowtorch for this job. Please don’t have your kid hand you a blowtorch—Ed.)
You’ll also need a flat workspace, such as a garage floor, driveway, or street parking that’s also well-ventilated. Check your local laws to make sure you’re not violating any codes when using the street because we aren’t getting your ride out of the clink.
How To Check Transmission Fluid
Consult your vehicle’s owner’s manual to determine whether or not your transmission fluid can be checked with a dipstick.
Vehicles Without Transmission Dipsticks
If your vehicle does not have a transmission dipstick, read your owner’s manual for instructions. It likely will tell you to have it serviced by a professional with the correct tools for the job.
Vehicles With Transmission Dipsticks
- Make sure your car is parked on a flat and level surface to ensure an accurate reading.
- Start your car to warm up the transmission and keep it in park or neutral, depending on the vehicle and manufacturer.
- Identify the dipstick, pull it out, and wipe the stick clean with a spare rag or towel.
- Place the dipstick all the way back into its original position.
- Remove the dipstick once again and locate the fluid level indicators on the stick. There might be two indicators for hot or cold temperatures.
- If the fluid is low, there’s likely a leak or issue that needs servicing.
NOTE: If you want to be absolutely sure there is a leak and don’t need to drive anywhere, you can add more transmission fluid and check the floor again the next day. However, a transmission is a pretty sealed-off system, and a leak is one of the only ways fluid can escape.
How To Add Transmission Fluid
- Read your owner’s manual to determine your car’s specific transmission fluid needs. Check for the specific type, as well as the amount.
- Locate the filler tube.
- Remove the dipstick.
- Place a funnel into the tube.
How To Change Transmission Fluid
Servicing the transmission will require you to jack the car up, get underneath, and remove the pan. A full flush will require professional help. For more information, visit The Drive’s detailed guide, How To Change Transmission Fluid.
Getting a Pro’s Help from YourMechanic
There’s nothing like getting midway through a job and finding yourself, well, stuck. Sometimes, it doesn’t affect driveability, other times, you may have shot yourself in the foot and can’t get to work. It’s then you need help ASAP, that’s why The Drive partnered with YourMechanic to help find you a local mechanic, get a quick quote, and back to work in time for your morning meeting. Use promo code THEDRIVE to save $10 off any appointment $70 or more.
You’ve got questions, The Drive has answers!
Q. What Happens If You Overfill Transmission Fluid?
A. Overfilling a transmission could cause damage to the transmission’s internal parts. If the transmission oil level is too high, it could submerge the gears, which could cause foaming, which could cause issues. The system requires specific levels to maintain specific pressures, and if it’s not on point, the transmission could act up and show physical symptoms such as leaks or malfunctioning.
Q. Can a Transmission Go Out Without Warning?
A. Never say never, but your transmission will almost always tell you it’s struggling before failing completely. This is why it’s important to consistently check and service your fluid to keep everything running like a synchronized swim team.
Q. Will Check Engine Light Come On If Transmission Fluid Is Low?
A. Most modern cars are equipped with some sort of warning light or alert when there is an issue with the transmission.
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