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Autopapyrus · Subaru Forester 2.5 FB25 (2017)
https://autopapyrus.com/guides/subaru/forester/coolant-replacement/
Compiled automatically from service literature and owner experience. Specs are for the typical configuration — check them against your exact car before you start.

Subaru Forester 2.5 FB25 (2017): Coolant Replacement

The FB25 engine is sensitive to coolant quality because of the high thermal loads of the horizontally opposed layout. Subaru's schedule calls for the first replacement at 160,000 km (100,000 miles) or 10 years, then every 80,000 km (50,000 miles) or 5 years. The system capacity is 7.4 L (7.8 qt), about 8 L (8.5 qt) including the reservoir, and about 5 L (5.3 qt) comes out when draining through the radiator.

Difficulty: Medium Time: 1.5-2 hours Steps: 13 Tools: jack and jack stands, protective gloves, drain pan (8-10 L / 8.5-10.5 qt), Phillips screwdriver, long-neck funnel

Part

  • 🔩 Subaru Super Coolant LLC SOA868V9270 (blue-green, pre-diluted 50/50), 2 jugs of 4 L (4.2 qt) each. Alternative: Ravenol LTC (Lobrid Technology Coolant) concentrate (mix 1:1 with distilled water)
There's a full repair manual for this car Every system, wiring diagrams and torque specs — not just this job. Haynes and 9 more. See manuals →

Step by step

13 steps
  1. Let the engine cool down completely, at least 3 hours after driving. Working on a hot system risks burns from pressurized coolant.
  2. Raise the front of the vehicle with the jack and set it on jack stands. Remove the plastic engine undercover: 4-6 bolts, 10 mm wrench.
  3. Place the drain pan under the lower right corner of the radiator. Locate the plastic drain valve (petcock) with a Phillips-type head at the bottom right of the radiator.
  4. Remove the coolant reservoir cap and the radiator cap (metal, on the left side of the engine under the hood). This speeds up draining and prevents a vacuum in the system.
  5. Using a Phillips screwdriver, slowly turn the petcock counterclockwise 3-4 turns. Let the coolant drain completely into the pan (about 5 L (5.3 qt), 10-15 minutes).
  6. Turn the petcock back in until it stops. Do not overtighten, as the plastic can crack. Lower the vehicle and reinstall the engine undercover.
  7. Slowly pour fresh coolant through the radiator filler neck until it reaches the level of the filler neck. Do not pour quickly, or air pockets will form.
  8. Top off the coolant reservoir to the FULL mark with the engine cold.
  9. Close the radiator cap. Start the engine, set the heater to maximum temperature and maximum fan speed. Hold the engine at 2000 rpm for about 10 minutes.
  10. Continue warming up at idle until the radiator cooling fan turns on, then let the fan shut off. Turn off the engine.
  11. Let it cool for 20-30 minutes. Check the level in the coolant reservoir and top off to FULL if needed. Check the level in the radiator through the filler neck and top off to the rim of the neck.
  12. Repeat the warm-up cycle (steps 9-10) once more to fully purge the air. Check for leaks under the vehicle and at the hose connections.
  13. The next day, check the level with the engine cold. Some settling is possible; top off if needed.

Common mistakes and warnings

  • FB25 engines are prone to air pockets in the cooling system, so thorough bleeding is mandatory. Insufficient air removal leads to overheating and head gasket damage. Use only genuine Subaru LLC or compatible carboxylate coolants. Silicate or hybrid types shorten the life of the water pump and thermostat. Do not mix different types of coolant.
How it works · 3D How the Engine Cooling System Works How the part you're working on actually works — in plain English, on a 3D model. Open in 3D →