How to tell if you need transmission fluid

How Do I Tell If My Transmission Fluid Is Bad?

Things such as trouble going into gear, hard shifts or thumps between gears, slipping or jumping gears, delay in acceleration, and strange noises such as whining or grinding are all signs it’s time to change the transmission fluid.

The transmission consists of about 800 parts, including gears, bell housing, and filters.

Transmission fluid is used in automatic transmission cars as a lubricant that keeps the transmission from overheating and helps power the transmission by creating pressure and torque. Transmission fluid can become dirty, contaminated and worn out. The transmission will not work correctly and ultimately overheat and break down if the fluid is not maintained properly.

Related: Automatic Transmission Fluid Overview

Transmission fluids vary widely in color.

Even new fluids can be vastly different – and the darkening of the transmission fluid over time is not abnormal. However, there is an exception to this rule. If you discover black or burnt fluid, this indicates there has already been a problem with the transmission and/or the fluid itself. Get your car to a transmission technician as soon as possible if you discover anything that indicates a harsh breakdown or burning fluid.

Check the transmission fluid regularly.

It is a good idea to check the transmission fluid about every 6 months. See this handy infographic for tips on checking transmission fluid.

Transmission fluid color is a good indicator of wear and tear.

Though color is a good visual way to estimate the age and condition of the transmission fluid, it is not necessarily an indicator of a terrible problem. The color of your transmission fluid is a good place to start when it comes to diagnosing issues, but it does not always give you an accurate measure of its condition. If in doubt, the best thing to do is have a professional transmission technician check the transmission, run a Vehicle Courtesy Check, and go from there. You might discover there is nothing major wrong, and all you need is a fluid change, or a transmission flush.

Related: Benefits of a Transmission Fluid Flush

How to tell if you need transmission fluid

What’s a transmission fluid flush?

A transmission flush uses pressurized force to send fresh oil and cleaning solvents through the system and remove all of the old fluid and contaminants. New oil is then pumped into the transmission. A transmission flush acts as a complete cleansing of all the old fluid, but if your transmission fluid has already been contaminated for some time, or the transmission has been running hot and experiencing problems, this procedure might not do much good.

AAMCO Colorado Transmission Repair Experts Can Help

If you are aware of problems, and have had your transmission serviced recently, a flush could help you get the most out of your transmission – consult a professional transmission mechanic. Don’t be afraid to ask questions, understand the process, and use your best judgement when deciding on how to maintain your transmission. Bring your vehicle into AAMCO Colorado for a FREE courtesy vehicle check and to ask us any questions you might have about your transmission.

If you have questions about your car’s road readiness, or about car repair and maintenance topics, AAMCO Colorado can help. You can also use the AAMCO Colorado Ask a Mechanic feature to submit your auto repair questions. They will be answered by a real AAMCO Colorado mechanic as soon as possible.

How to tell if you need transmission fluid

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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.

Always use the manufacturer-recommended automatic transmission fluid., Amazon / Honda

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

Safety

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.

  • Mechanic gloves
  • Safety glasses

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.

Tool List

  • Funnel
  • Dirty cloth, shirt, sock, or microfiber towel
  • Socket set

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.

Transmission are one of the most complicated devices on a car., Depositphotos

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

  1. Make sure your car is parked on a flat and level surface to ensure an accurate reading.
  2. Start your car to warm up the transmission and keep it in park or neutral, depending on the vehicle and manufacturer.
  3. Identify the dipstick, pull it out, and wipe the stick clean with a spare rag or towel.
  4. Place the dipstick all the way back into its original position.
  5. Remove the dipstick once again and locate the fluid level indicators on the stick. There might be two indicators for hot or cold temperatures.
  6. 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

  1. Read your owner’s manual to determine your car’s specific transmission fluid needs. Check for the specific type, as well as the amount.
  2. Locate the filler tube.
  3. Remove the dipstick.
  4. 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.

FAQs (H2)

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.

How do I know if my transmission fluid needs to be filled?

6 Signs Your Transmission Fluid is Bad and Needs Changing.
Dirty transmission fluid..
Transmission whining noise..
Gears slipping..
Can't go into reverse gear..
Slipping out of gear..
Engine running hot..
Grinding noise..

What happens when you are low on transmission fluid?

When your transmission fluid is low, your car won't generate as much hydraulic pressure, leading to what's known as gear slippage. Gear slippage commonly manifests as a failure to accelerate properly. When your transmission fluid is low, you may notice your vehicle reaching high RPMs while moving sluggishly.

How do I check if my transmission fluid is low?

Vehicles With Transmission Dipsticks 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.

What does low transmission fluid sound like?

Gurgling. 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.