2018 Subaru Crosstrek Coolant Capacity, Type, and Service Guide

The 2018 Subaru Crosstrek holds approximately 7.1 to 7.2 quarts (6.7 to 6.8 liters) of coolant, depending on whether it is equipped with a CVT or a manual transmission. As an ASE-certified master technician, I frequently see these rugged hatchbacks in the bay, and keeping their boxer engines cool is critical to their longevity. Below is your comprehensive guide to the coolant capacity, factory specifications, and service procedures for the 2018 Subaru Crosstrek.

Quick answer

When servicing the cooling system on your 2018 Crosstrek, keep these factory specifications in mind:

• Total Cooling System Capacity: 7.1 quarts (6.7 liters) for CVT models; 7.2 quarts (6.8 liters) for Manual transmission models.
• OEM Coolant Spec: Subaru Super Coolant. It is a Phosphated Non-Amine Organic Acid Technology (P-OAT) coolant.
• Coolant Color: Blue.
• Mix Ratio: 50/50 pre-mixed formulation (do not add water if using the pre-diluted jug).

Capacity by engine option

For the 2018 model year, the Subaru Crosstrek was offered in North America with a single engine option—the updated 2.0-liter FB20D naturally aspirated flat-four. The minor capacity difference comes down to the transmission pairing.

Note: Total capacity includes the radiator, engine block, heater core, and coolant reservoir. A standard drain-and-fill will usually require slightly less than the total capacity.

Flush interval

Subaru utilizes an extended-life coolant, meaning you don't have to flush the system as often as older vehicles. However, adherence to this schedule is mandatory to prevent head gasket and water pump degradation.

• Normal Duty: The initial factory fill is rated for 11 years or 137,500 miles (220,000 km), whichever comes first. Subsequent replacements should be performed every 6 years or 75,000 miles (120,000 km).
• Severe Duty: If you frequently tow, off-road, or idle extensively in extreme temperatures, consider inspecting the coolant condition around 80,000 miles and shortening the replacement interval to every 5 years or 60,000 miles after the first flush.

How to refill & bleed

Subaru boxer engines are notorious for trapping air in the cooling system. If not bled correctly, an air pocket will cause the engine to overheat rapidly and the heater to blow cold air.

1. Drain the System: With the engine cold, open the petcock at the bottom of the radiator. Drain into a suitable catch pan.
2. Refill: Close the petcock. Use a spill-free funnel attached to the radiator cap neck. Pour in the 50/50 pre-mixed Subaru Blue Super Coolant slowly to allow air to escape. Fill the overflow reservoir to the "FULL" cold mark.
3. Bleed the Air: Start the engine and turn the climate control heat to maximum with the fan on low. This opens the heater core.
4. Burp the System: Let the vehicle idle. Gently squeeze the upper and lower radiator hoses to force trapped air bubbles up into the funnel.
5. Wait for the Thermostat: Once the cooling fans cycle on, the thermostat has opened. Top off the funnel as the fluid level drops.
6. Final Check: Shut off the engine, remove the funnel, install the radiator cap, and test drive. Let it cool completely and recheck the reservoir level.

Pro-Tip: To save time and guarantee a completely air-free system, I highly recommend using a pneumatic vacuum coolant filler. This tool draws a vacuum on the system and sucks the new coolant in, entirely eliminating air pockets.

Common cooling system issues

The 2018 Crosstrek (second generation) is generally highly reliable, but there are a few cooling system items to watch out for as the mileage climbs:

• Thermo Control Valve (TCV) Failure: Subaru moved away from traditional wax-pellet thermostats in some modern applications in favor of electronic thermo-control valves. These can occasionally fail, throwing a Check Engine Light and causing the vehicle to take a long time to warm up (or risk overheating).
• Radiator End Tank Leaks: Like most modern vehicles, the Crosstrek uses an aluminum radiator with plastic end tanks. Over time and thousands of heat cycles, the plastic can become brittle and seep coolant along the crimped seams.
• Water Pump Weepage: While much improved over older generations, the FB20 engine's water pump can still develop a slow weep from the weep hole as the internal seal wears out, usually past the 100,000-mile mark.

Keeping up with your coolant changes using the correct P-OAT blue fluid is the best way to prevent premature failures. If you need help servicing your cooling system or diagnosing a leak, don't leave it to chance. Find a trusted shop on Repairius.