2019 Highlander XLE Coolant Flush - When and what type?

ClearTheCode admin answer:

Your 2019 Toyota Highlander XLE with the 3.5L V6 uses Toyota's Super Long Life Coolant (SLLC), which is a pink/red, phosphate-free, silicate-free, and borate-free ethylene-glycol based coolant. This coolant is indeed designed for extended intervals, but not indefinitely.

Recommended Maintenance Schedule for SLLC:

1. First Change: Toyota typically recommends the first coolant change at 100,000 miles or 10 years, whichever comes first.
2. Subsequent Changes: After the initial change, the interval is usually every 50,000 miles or 5 years.

At 60,000 miles, you are likely still within the initial service interval, so a full flush might not be strictly necessary according to Toyota's schedule. However, factors like driving in extreme conditions (very hot/cold climates, heavy towing) or if the coolant looks discolored or sludgy, might warrant an earlier service.

Coolant Type:

• ONLY use Toyota Super Long Life Coolant (SLLC), or an equivalent aftermarket coolant that explicitly states it meets Toyota's SLLC specifications (usually pink/red in color). Mixing different types of coolants can lead to chemical reactions that damage your cooling system components.
• SLLC is pre-diluted, meaning it's already a 50/50 mix of coolant and deionized water. Do not add straight concentrate unless you are specifically diluting it with distilled water.

DIY Tips for a Drain and Fill (not a full flush):

1. Safety First: Ensure the engine is completely cool before working on the cooling system. Wear gloves and eye protection.
2. Locate Drain Plug: Find the drain plug on the bottom of the radiator. Place a large drain pan underneath.
3. Drain Coolant: Open the radiator drain plug and the radiator cap (or reservoir cap) to allow the coolant to drain. Some models may also have engine block drain plugs, but these are often skipped for a simple drain and fill.
4. Refill: Close the drain plug. Slowly pour new SLLC into the radiator, then the reservoir, until full. Start the engine with the heater on full blast and allow it to warm up, topping off the coolant as air bubbles escape (burping the system). This is crucial to prevent air pockets.
5. Monitor: Drive the vehicle, then recheck the coolant level in the reservoir once the engine cools down, topping off if needed.

When to see a shop:

• If you're unsure about the process, especially ensuring all air is bled from the system.
• If your coolant looks unusually dark, sludgy, or has oil contamination, which could indicate a more serious issue.
• For a complete system flush, which involves specialized equipment to remove all old coolant and contaminants, a professional shop is recommended.