Transmission Fluid Change: Ultimate Guide

Your car’s fluids are its lifeblood. When they get old, brown, and sludgy, it’s detrimental to the vehicle and to the size of your bank account. One such necessary fluid that people often dismiss is your transmission fluid. This thick oil keeps the transmission’s mechanicals lubricated, and if it’s ignored, you’ll potentially be staring down a massive repair bill 

There are thousands of online tutorials and guides about why you need to change your oil, but not too many on why you should absolutely change your transmission fluid. To better inform readers and DIY’ers everywhere on the importance of this crucial liquid, The Drive’s crack informational team has put together a guide answering all your most important questions about transmission fluid.  

Taking up the charge, we’ve dedicated Guides and Gear’s channel today to explaining just exactly what happens when you don’t change your transmission fluid, as well as how to change it yourself. 

Socket wrench at the ready!

Transmission fluid is the viscous oil that allows the transmission to function without failure. By lubricating the transmission’s internals, the fluid prevents heat build-up and wear and tear of metal-on-metal. Transmission fluid is typically colored red or green to help DIYers distinguish it from conventional motor oil. 

Most transmission fluid is designed to last for up to 100,000 miles. There are a few with higher limits, though it’s still recommended you change your fluid at 100,000 miles or close to it. 

Depending on the level of abuse you dole out, unchanged transmission fluid could seize, evaporate, seep out, and cause catastrophic transmission failure. So if you don’t want to be out a couple thousand dollars, it’s best you check your transmission fluid from time to time. 

First, there are a few things you need to know.

Estimated Time Needed: Half-hour 

Skill Level: Beginner

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 die, get maimed, or lose a finger.

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 to change your spark plugs 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 still 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 to change your transmission fluid. 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.4

Let’s do this! 

You’re done!

The Drive recognizes that while our How-To guides are detailed and easily followed, a rusty bolt, an engine component not in the correct position, or oil leaking everywhere can derail a project. That’s why we’ve partnered with JustAnswer, which connects you to certified mechanics around the globe, to get you through even the toughest jobs. 

So if you have a question or are stuck, click here and talk to a mechanic near you.

You’ve got questions, The Drive’s informational team has answers!

You can! Underneath your hood is a transmission fluid dipstick, similar to an oil dipstick, that allows you to check the level and condition of your fluid.

As mentioned, most transmission fluid will last around 100,000 miles. But it’s important to periodically check your transmission fluid, an act that takes all of a few seconds and could save you thousands of dollars in repair bills.

If you have a dealership or third-party mechanic do the transmission fluid flush, you’re looking at a range of $80-$250. DIYers will have considerably smaller bills, ranging from $25-$50 depending on how much fluid your car takes.

Castrol Transmax Dex/Merc ATF

ACDelco Dexron VI Synthetic ATF

Red Line GL-4 Manual Transmission Lubricant

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