2023 Subaru Forester Coolant Capacity & Type

The 2023 Subaru Forester holds approximately 7.6 quarts (7.2 liters) of coolant in its cooling system.

Quick Answer

• Total Cooling System Capacity: Approximately 7.6 quarts (7.2 liters)
• OEM Coolant Specification: Subaru Super Coolant (Blue, HOAT - Hybrid Organic Acid Technology). This is a factory fill, long-life coolant.
• Mix Ratio: 50/50 prediluted or 50/50 mix of concentrate with distilled water.

Capacity by Engine Option

The 2023 Subaru Forester is primarily offered with one engine option, the 2.5L DOHC FB25D engine. The cooling system capacity for this engine is as follows:

Flush Interval

Subaru recommends specific flush intervals for their Super Coolant, which is a long-life formulation:

• Normal Duty: The initial coolant replacement is recommended at 137,500 miles or 11 years, whichever comes first. Subsequent replacements are then recommended every 75,000 miles or 6 years.
• Severe Duty: If your vehicle is subjected to severe driving conditions (e.g., frequent towing, driving in extreme temperatures, or dusty conditions), it's advisable to inspect the coolant more frequently and consider replacing it sooner, typically around 75,000 miles or 6 years.

How to Refill & Bleed

Properly refilling and bleeding the cooling system in a 2023 Subaru Forester is crucial to prevent air pockets, which can lead to overheating. Here's a general procedure:

1. Safety First: Ensure the engine is completely cool before starting. Wear appropriate safety gear, including gloves and eye protection.
2. Drain the System: Locate the radiator drain plug (petcock) at the bottom of the radiator and open it to drain the old coolant into a suitable container. Some models may also have engine block drain bolts.
3. Flush (Optional but Recommended): If you are performing a full flush, close the drain plug and fill the system with distilled water. Run the engine with the heater on high until it reaches operating temperature, then drain. Repeat until the drained water is clear. You can use a cooling system flush product if desired, following the product's instructions.
4. Close Drains & Refill: Close all drain plugs. Slowly fill the radiator with the Subaru Super Coolant 50/50 pre-mix or a 50/50 mix of concentrate and distilled water. Fill the coolant reservoir to the "FULL" mark.
5. Bleed the System:
   • Start the engine and let it idle with the radiator cap off. Set the cabin heater to its maximum heat setting and fan speed on low to open the heater core valve.
   • As the engine warms up, the thermostat will open, and coolant will begin to circulate. You may see air bubbles escape from the radiator filler neck. Squeeze the upper and lower radiator hoses to help dislodge air pockets.
   • Maintain the coolant level in the radiator by adding more as needed until no more bubbles appear and the level stabilizes.
   • Install the radiator cap, ensuring it's tightened securely.
   • Drive the vehicle for a short period, then let it cool down completely. Check the coolant level in the reservoir and top it off if necessary. Repeat this process over the next few driving cycles until the level remains stable.
   • Special Note: Subaru vehicles are generally known for being somewhat sensitive to air in the cooling system. If you're having difficulty bleeding, a vacuum fill tool can be very effective at removing all air from the system.

Common Cooling System Issues for this Generation

The fifth-generation Subaru Forester (2019-present) is generally reliable, but like any vehicle, it can experience cooling system issues. Some common points to be aware of include:

• Water Pump Leaks: While not extremely common, water pump seals can eventually wear, leading to coolant leaks. Keep an eye out for pink or blue-ish residue near the front of the engine.
• Radiator Leaks: Radiators can develop leaks over time, especially at the plastic end tanks. Small cracks can form, leading to a slow loss of coolant.
• Thermostat Failure: A failing thermostat can cause the engine to overheat (if stuck closed) or run too cool (if stuck open). Symptoms include fluctuating temperature gauges or persistent overheating/underheating.
• Hose Leaks: Rubber hoses can degrade and crack, leading to coolant leaks. Inspect hoses for cracks, bulges, or softness.
• Head Gasket Issues: While less prevalent in newer Subaru generations compared to the past, head gasket failures can still occur, leading to external coolant leaks, coolant consumption, or mixing of oil and coolant. Keep an eye on coolant levels and oil appearance.

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