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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.

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.

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.

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.

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.

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:

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

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.

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.

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.

Consult your vehicle’s owner’s manual to determine whether or not your transmission fluid can be checked with a dipstick.

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.

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.

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.

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!

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.

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.

A. Most modern cars are equipped with some sort of warning light or alert when there is an issue with the transmission.

Red Line API GL-4 Manual Transmission and Transaxle Lubricant

ACDelco Professional Dexron Synthetic Automatic Transmission Fluid

Castrol Transmax Dex/Merc Synthetic Automatic Transmission Fluid

Got a question? Got a pro tip? Send us a note: guidesandgear@thedrive.com

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