2018 Subaru Crosstrek — Fluid Type Specs

Quick reference

Fluid	Type/Spec	Capacity
Engine oil	0W-20 full synthetic; API SN (Resource Conserving) or newer, ILSAC GF-5/GF-6	Approx. 4.6–5.1 qt (4.4–4.8 L) with filter — verify by VIN in owner’s manual/OEM info
Engine coolant	Subaru Super Coolant (blue), P-OAT/Phosphate Organic Acid Technology; silicate/borate-free; premix 50/50	Approx. 6.9–7.6 qt (6.5–7.2 L) total — verify
Transmission (CVT)	Subaru CVTF for Lineartronic (CVTF-II/Lineartronic); use only Subaru-spec CVT fluid	Service fill ~5–7 qt (4.7–6.6 L); total ~12–13 qt (11–12.3 L) — verify by trans code/TR580
Transmission (6‑speed manual)	API GL-5 75W-90 gear oil (Subaru Gear Oil 75W-90/Extra-S equivalent)	Approx. 3.2–3.7 qt (3.0–3.5 L) — verify
Transfer case	Not separate on Crosstrek; integrated into transaxle (CVT uses CVTF; 6MT shares with trans/diff)	N/A (uses fluids listed above)
Front differential (CVT models)	API GL-5 75W-90 gear oil	Approx. 1.3–1.6 qt (1.2–1.5 L) — verify
Rear differential	API GL-5 75W-90 gear oil (no LSD additive required)	Approx. 0.8–1.0 qt (0.75–0.95 L) — verify
Brake fluid	FMVSS No. 116 DOT 3 (DOT 4 acceptable if compatible)	Fill to MAX line; typical flush uses 1–2 qt (0.95–1.9 L)
Power steering	Electric power steering (EPS) — no hydraulic fluid	N/A
Windshield washer	Conventional -20°F (-29°C) methanol-based washer fluid	Approx. 3–4 qt (2.8–3.8 L)
Diesel Exhaust Fluid (DEF)	Not applicable (gasoline engine)	N/A

Engine oil (2.0L FB-series)

• Spec: 0W-20 full synthetic meeting API SN (Resource Conserving) or newer and ILSAC GF-5 (GF-6 acceptable and backward-compatible). Subaru does not publish a unique oil chemistry spec number beyond API/ILSAC for this engine.
• Capacity: Typically 4.6–5.1 quarts (with filter), depending on production/market. Always verify by VIN in the owner’s manual or OEM service information.
• Interval: Follow Subaru’s maintenance schedule. Many 2018 models specify around 6,000 miles/6 months under normal service; shorten under severe service (repeated short trips, extreme temps, dust).
• Notes/pitfalls:
  • Always replace the crush washer on the drain plug.
  • Do not substitute heavier viscosity unless directed by Subaru; 0W-20 supports proper VVT operation and fuel economy.
  • If oil consumption is noted, document and monitor; use only API/ILSAC-approved oils.

Engine coolant

• Spec: Subaru Super Coolant (blue), a phosphate organic acid technology (P-OAT) formula; silicate/borate/nitrite-free. Use premixed 50/50 Subaru Super Coolant or distilled water with Subaru concentrate. Color: blue.
• Capacity: Approx. 6.9–7.6 quarts total; confirm exact volume for your VIN.
• Interval: Long-life chemistry; Subaru commonly specifies extended initial service (on the order of 10–11 years/100k+ miles) with subsequent shorter intervals. Verify exact interval for your vehicle.
• Notes/pitfalls:
  • Do not mix with conventional green or universal HOAT/OAT coolants; color alone is not a guarantee of compatibility.
  • Proper air bleeding is critical on FB engines to avoid hot spots; use the OEM fill/bleed procedure and heater on HOT during fill.

Transmission fluid — CVT (Lineartronic, e.g., TR580)

• Spec: Subaru CVT Fluid for Lineartronic (often labeled CVTF-II/Lineartronic). Use only Subaru-approved CVT fluid; do not use Dexron/Mercon or “universal” ATF.
• Capacity: Service drain/refill typically 5–7 quarts; total dry fill ~12–13 quarts. Exact volume depends on unit and service method.
• Interval: Subaru generally calls CVT fluid "inspect" with replacement under severe use (towing, mountainous driving, heat, frequent short trips). Many shops target 60k–100k miles for preventive service. Verify by VIN.
• Notes/pitfalls:
  • Fluid level setting requires specific temperature and a level plug procedure; use a scan tool/thermometer per OEM steps.
  • Keep the fill area and fittings meticulously clean to prevent valve body contamination.

Transmission fluid — 6-speed manual

• Spec: API GL-5 75W-90 gear oil (Subaru Gear Oil 75W-90/"Extra-S" equivalent). Do not use GL-4.
• Capacity: Approx. 3.2–3.7 quarts. Verify for your build code.
• Interval: Typically inspected regularly; many owners service between 30k–60k miles depending on usage.
• Notes/pitfalls:
  • Cold shifting feel varies by brand; stick with GL-5 oils known to perform well in Subaru synchromesh boxes.
  • Replace crush washers and torque to spec.

Transfer case

• The Crosstrek does not use a separate truck-style transfer case. On CVT models, the transfer gears are lubricated by CVT fluid. On manual models, the center/front differential is integrated with the transmission and uses the same GL-5 gear oil. No separate fluid.

Front differential (CVT models)

• Spec: API GL-5 75W-90 gear oil.
• Capacity: Approx. 1.3–1.6 quarts.
• Interval: Often serviced 30k–60k miles depending on duty cycle.
• Notes/pitfalls:
  • The front differential has its own fill/drain separate from the CVT; do not overfill or cross-fill with CVT fluid.

Rear differential

• Spec: API GL-5 75W-90 gear oil. No limited-slip additive is required (rear diff is open on most 2018 Crosstreks). If equipped with an LSD (rare/special models), follow LSD oil/additive guidance accordingly.
• Capacity: Approx. 0.8–1.0 quarts.
• Interval: Similar to front diff; 30k–60k miles is a common service window depending on use.
• Notes/pitfalls:
  • Clean magnet and replace crush washers. Check for water intrusion if the vehicle has been submerged.

Brake fluid

• Spec: FMVSS No. 116 DOT 3. DOT 4 is acceptable if compatible and from a reputable brand; do not mix with DOT 5 (silicone).
• Capacity: Fill to MAX in reservoir; a complete flush typically consumes 1–2 quarts.
• Interval: Commonly every 2–3 years regardless of mileage due to moisture absorption; verify Subaru’s schedule.
• Notes/pitfalls:
  • Keep fluid off painted surfaces; always perform ABS bleed procedures if required after component replacement.

Power steering

• The 2018 Crosstrek uses electric power steering (EPS). There is no serviceable hydraulic power steering fluid.

Windshield washer fluid

• Spec: Standard methanol-based washer fluid appropriate for your climate (e.g., -20°F/-29°C winter blend). Rain-repellent variants are optional.
• Capacity: Approximately 3–4 quarts.
• Interval: Top off as needed. In freezing climates, purge summer fluid before first freeze.

Diesel Exhaust Fluid (DEF)

• Not applicable — the 2018 Crosstrek is gasoline-powered, so DEF (ISO 22241) is not used.

Verify all capacities and specifications with the owner’s manual or OEM service information for your exact VIN, transmission type, and market. When in doubt, use Subaru-branded fluids or those explicitly stating compliance with the specifications listed above.

Find a trusted shop on Repairius.