Quick answer: Transmission Fluid Change on a 2010–2017 GMC Terrain is rated Moderate and takes about 1 hour. You'll need 9 tools for this job, and parts cost about $85. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name |
Part Number |
Price |
Buy |
| Automatic Transmission Fluid (ATF) |
88861003 |
$50.00 |
|
| Transmission Drain Plug Gasket |
24237093 |
$5.00 |
|
| Transmission Filter |
24237094 |
$30.00 |
|
About prices: shown prices are typical retail averages and change frequently; cheaper alternatives may be available. Confirm the current price before buying.
💡 Pro tip: Order all parts at once to save on shipping
Step-by-Step Instructions
Follow these steps carefully
1
Prepare (DEXRON VI, two-person job!)
The 2010–2017 GMC Terrain (6T40 2.4L / 6T45 V6, 6-speed automatic) transmission fluid change: use DEXRON VI ATF ONLY. You'll need: DEXRON VI (buy 6 quarts — you'll drain ~5), 11mm socket, long flexible funnel, drain pan. The Terrain has NO dipstick — fill through the TOP fill cap, level via the side check plug. CRITICAL: the level check requires the engine RUNNING at 85-95°C (185-203°F). The vehicle must be running during filling or fluid pours back out at ~4 qt. This is a two-person job (one fills, one monitors the check plug). Park on level ground. The 6T40 and 6T45 share the procedure.
🔧 Mechanic's note — Tom Becker
I always read that twice: engine running during the fill, or the fluid pours right back out at four quarts. This is the quirk that ruins the job for solo first-timers — bring a helper and a scan tool that reads trans temp.
2
Drain via 11mm Plug
Locate the 11mm drain plug (passenger-side bottom of the transmission case). Position the drain pan. Remove the drain plug — let the ATF drain (expect ~4.5-5 quarts). The Terrain's 6T40 drains about half its fluid — the torque converter holds the rest. A drain-and-fill (~5 qt) is the service — the pan filter is replaceable with a pan drop, but that's messy; the simple DIY is drain-and-fill leaving the pan on.
3
Reinstall Drain Plug
Reinstall the drain plug. Torque spec wasn't verified for the drain plug — tighten snugly (the check plug is 106 lb-in / 12 N·m, but don't assume the drain is the same). The 6T40's pan filter is inside — not changed at drain-and-fill.
4
Fill via Top (engine RUNNING!)
Remove the TOP fill cap. With the engine RUNNING, add DEXRON VI through the top fill hole using a long flexible funnel. Have a helper monitor the side check plug. Don't use Dexron III or universal — DEXRON VI only.
5
Set Level at 185-203°F (engine running!)
Set the level: vehicle LEVEL, engine RUNNING, trans in PARK, ATF at 85-95°C (185-203°F) — read via scan tool. Remove the side oil level set plug (11mm). Correct = fluid just drips out. If none, add until it drips. If steady stream, wait for drips. Reinstall the check plug — torque to 106 lb-in (12 N·m). The 185-203°F window with engine running is the GM procedure — don't check cold or with engine off.
🔧 Mechanic's note — Ray Delgado
I know drips, not a stream — that's the whole level check. Pull the plug and let it settle; if it's still streaming, wait. Rushing this step is how transmissions end up overfilled and shifting like they're drunk.
6
Check Leaks and Test
Reinstall the fill cap. Check for leaks. Reset the transmission oil life monitor if equipped. The Terrain should shift smoothly. Owner consensus: drain-and-fill every ~50,000 miles (not a GM factory figure — owner practice). A single drain-and-fill replaces ~half the fluid; sequential drain-and-fills (at consecutive oil changes) refresh most of it without a flush. The NO-dipstick top-fill with engine-running level check at 185-203°F is the Terrain's defining procedure. The 6T40/6T45's 11mm drain and side check plug are the hardware cues. (This guide was rewritten — a previous version had incorrect content.)
All Done!
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
- • Overfilling the transmission fluid
- • Using incorrect type of transmission fluid
- • Not properly securing the vehicle before starting the repair
