Quick answer: Coolant Flush and Fill on a 2016–2022 Lexus RX is rated Moderate and takes about 2–3 hours. You'll need 7 tools for this job, and parts cost about $32. This guide walks you through the full job step by step, including the mistakes to avoid.
| Part Name |
Part Number |
Price |
Buy |
| Toyota/Lexus Genuine Super Long Life Coolant |
00272-SLLC2 |
$30.00 |
|
| Drain Plug Washer |
16492-21050 |
$2.00 |
|
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
Prep cold and remove the V-bank engine cover
Work only on a stone-cold engine — the 2016–2022 RX (fourth generation) runs a 2GR-FKS V6 that holds heat a long time. Open the hood and remove the big plastic V-bank cover over the engine: place both hands on its sides and lift straight up to pop the front clips, then the rear clip. Set it somewhere it will not get stepped on. While you are in there, check your owner's manual for the exact coolant specification — these vehicles are factory-filled with Toyota Super Long Life Coolant (pink), and your manual is the authority on what goes back in. Note the reservoir tank on the side of the bay with its FULL line.
🔧 Mechanic's note — Tom Becker
I prep the RX cold and remove the V-bank cover — I confirm the Toyota coolant spec first. I have seen mixed coolants gel up and clog a heater core, so I drain it all and start fresh with the right stuff.
2
Remove the side cover and intake duct seal
The fourth-gen RX buries the radiator area under trim, so clear it out of the way. Remove the engine room side cover — it is held by four push clips — and then the cool air intake duct seal across the front, which has seven clips. Use a trim tool so you do not snap the clip heads. With those off you can see the radiator, the radiator cap on the filler neck, and the white plastic radiator drain cock plug at the bottom of the radiator. Position a wide, low drain pan underneath before you touch anything.
3
Open the radiator drain cock and both block drains
Here is where the 2016–2022 RX differs from a simple radiator drain: the service procedure calls for three drain points. Let the system drip until the flow stops completely before moving on.
4
Run distilled-water flush cycles
Snug all three drain cocks closed temporarily and fill the radiator through the filler neck with distilled water. Start the engine with the cabin heater set to full hot and let it idle until the thermostat opens and the radiator fan cycles — this circulates water through the block and heater core. Shut it off, let it cool completely, then reopen the radiator drain cock and both block drains and empty it all again. Repeat until the drained water runs clear. Also pull the reservoir tank, rinse out any sediment with clean water, and reinstall it. Never substitute plain tap water for the final fill.
5
Close the drains and refill with fresh coolant
Tighten the radiator drain cock plug by hand and torque the two cylinder block drain cocks to 13 N·m (about 9 ft-lbs) — snug, not gorilla-tight, since the plugs are brass and the threads are easy to damage. Now fill through the radiator filler neck (the water outlet opening) with fresh Toyota Super Long Life Coolant or the equivalent your owner's manual specifies, premixed as directed. Pour slowly so air can escape upward. Fill the radiator to the neck, then fill the reservoir tank up to the FULL line. Install the radiator cap firmly.
🔧 Mechanic's note — Ray Delgado
I close the Lexus coolant drains and torque them — I have seen a plastic drain petcock snap off from overtightening, and then you are fishing pieces out of the radiator. The wrench keeps my enthusiasm in check.
6
Bleed air with the warm-up and rev sequence
Air bleeding is critical on the 2GR-FKS. Start the engine and warm it until the thermostat opens, keeping the heater on hot. Hold the engine at 2,500–3,000 rpm for a few minutes while wearing gloves, then carefully press the inlet and outlet radiator hoses several times by hand to burp trapped air — keep your hands and sleeves well clear of the spinning radiator fan. Shut the engine off and let it cool to ambient temperature. Check the reservoir: if the level has dropped below the FULL line, add coolant back up to FULL. Repeat the warm-up once more if the heater output feels uneven.
🔧 Mechanic's note — Ray Delgado
I bleed the RX cooling system with the warm-up and rev sequence — I have learned that the V-bank traps air. I take the extra ten minutes because trapped air causes the comebacks nobody wants.
7
Reinstall trim, road test, and do the morning check
Take the RX for a 20-minute drive, watching the temperature gauge for any creep above normal. Scan the ground under the radiator and block drains for drips. Deliver the old coolant to a recycling point; do not pour it out anywhere.
All Done!
Test your repair before closing everything up. If something doesn't work right, double-check your steps.
⚠️ Common Mistakes to Avoid
- • Draining only the radiator and leaving old coolant in the block — this RX has two block drains for a reason
- • Overtightening the brass block drain plugs and stripping the threads
- • Skipping the rev-and-squeeze bleed and ending up with an air-locked heater core
- • Forgetting to reinstall all the intake duct and side cover clips
