2018 Toyota Highlander Coolant Capacity and Type

The 2018 Toyota Highlander holds between 6.5 and 10.1 quarts (6.2 and 9.6 liters) of coolant, depending on the engine and drivetrain configuration.

Quick Answer

• Total Cooling System Capacity: 6.5 to 10.1 quarts (6.2 to 9.6 liters)
• OEM Coolant Specification: Toyota Super Long Life Coolant (SLLC)
• Color: Pink
• Chemistry: HOAT (Hybrid Organic Acid Technology)
• Mix Ratio: 50/50 with deionized water (typically sold as a pre-mix)

Capacity by Engine Option

The 2018 Highlander was available with two engine options, a 2.7L four-cylinder and a 3.5L V6, with different capacities for front-wheel drive (FWD) and all-wheel drive (AWD) models.

Flush Interval

Toyota recommends a very long initial service interval for the factory-fill coolant, followed by a more frequent schedule for subsequent flushes.

• Normal Duty: The first coolant change is recommended at 100,000 miles or 10 years. After the initial change, the interval is every 50,000 miles or 5 years.
• Severe Duty: If the vehicle is frequently used for towing, driven on dusty or dirty roads, or used for extensive idling (like police, taxi, or delivery services), it is wise to consider a shorter interval, such as every 60,000 to 75,000 miles.

How to Refill & Bleed

Properly refilling and bleeding the air from the cooling system is critical to prevent overheating. While a simple drain and fill of the radiator is straightforward, a full system flush requires ensuring no air pockets are trapped.

1. Drain: With the engine cool, open the petcock at the bottom of the radiator to drain the old coolant. Additional engine block drain plugs may exist for a more complete drain.
2. Refill: Use a spill-proof funnel that seals to the radiator neck. Slowly pour in the 50/50 pre-mixed Toyota Super Long Life Coolant until the funnel is about one-third full.
3. Bleed Air: Start the engine and turn the heater to the highest temperature and fan setting. As the engine warms up and the thermostat opens, you will see air bubbles coming up into the funnel. Continue to add coolant to the funnel to keep the level steady as the system purges air.
4. Special Note: The 3.5L V6 engine (2GR-FKS) has a bleed valve on the thermostat housing to aid in releasing trapped air. It's highly recommended to open this valve during the filling process. Many technicians prefer using a vacuum-fill tool on these systems to ensure no air is trapped, as they can be difficult to bleed completely otherwise.
5. Finalize: Once the bubbling stops and the engine reaches operating temperature, shut it off and let it cool completely. Remove the funnel, top off the radiator if needed, and fill the coolant overflow reservoir to the "FULL" line.

Common Cooling System Issues (2014-2019 Highlander)

This generation of the Highlander is known for its reliability, but like any vehicle, some issues can arise.

• Water Pump: While not rampant, there have been some reports of premature water pump failure, identifiable by a coolant leak from the front passenger side of the engine or a grinding noise.
• Radiator Leaks: Over time, the plastic end tanks of the radiator can develop hairline cracks, leading to slow coolant loss and potential overheating. Stains or a sweet smell of coolant around the front of the vehicle are key indicators.
• Sticking Thermostat: A thermostat that fails in the closed position will cause rapid overheating. If it fails in the open position, the engine will be slow to warm up and may trigger a check engine light.

Following the correct service procedures and using the specified OEM coolant will ensure the longevity and reliability of your Highlander's cooling system. Find a trusted shop on Repairius.