2015 Subaru Forester Fluid Type Specifications

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil	0W-20, API SN Plus or later, ILSAC GF-5 or GF-6	4.4 US Quarts (with filter)
Engine Coolant	Subaru Super Coolant (Blue), SLLC (OAT)	7.6 US Quarts
CVT Fluid	Subaru CVTF-II	13.0 US Quarts (initial fill)
Manual Trans. Fluid	Subaru Extra MT 75W-90, API GL-5	4.3 US Quarts
Front Differential	75W-90, API GL-5 (integrated with manual trans.)	4.3 US Quarts (shared)
Rear Differential	75W-90, API GL-5	0.8 US Quarts
Brake Fluid	DOT 3 or DOT 4	Varies
Power Steering	N/A (Electric Power Steering)	N/A
Washer Fluid	All-season washer fluid	1.3 US Quarts
DEF	Not Applicable (Gasoline Engine)	N/A

Engine Oil

For the 2015 Subaru Forester, the manufacturer specifies 0W-20 viscosity engine oil. It's crucial to use oil that meets or exceeds API SN Plus (or later) and ILSAC GF-5 (or later) standards. These specifications ensure the oil provides adequate protection against low-speed pre-ignition (LSPI), which can be a concern for direct-injected engines.

Capacity: Approximately 4.4 US Quarts with a filter change.

Intervals: Subaru recommends engine oil and filter changes every 6,000 miles or 6 months, whichever comes first, under normal driving conditions. For severe driving conditions (e.g., frequent short trips, extreme temperatures, towing), more frequent changes may be necessary. Always refer to your owner's manual for the most accurate and up-to-date service intervals.

Pitfalls: Always use the specified 0W-20 viscosity. Using a heavier weight oil can reduce fuel economy and potentially lead to increased engine wear, especially during cold starts. Conversely, using a lighter weight oil than specified can compromise engine protection under high-stress conditions. Ensure the oil carries the correct API and ILSAC certifications to guarantee proper engine protection.

Engine Coolant

The 2015 Subaru Forester uses Subaru Super Coolant, which is a blue-colored, long-life organic acid technology (OAT) coolant. Subaru's specific formulation, sometimes referred to as Super Long Life Coolant (SLLC), is designed for extended service intervals and provides excellent corrosion protection for Subaru's unique engine materials.

Capacity: Approximately 7.6 US Quarts.

Intervals: The initial replacement interval for Subaru Super Coolant is typically 137,500 miles or 11 years. After the initial replacement, subsequent changes are recommended every 75,000 miles or 6 years. Always verify these intervals in your owner's manual.

Pitfalls: Never mix Subaru Super Coolant with conventional green, yellow, or even other red/pink OAT coolants. Mixing different coolant types can lead to chemical incompatibilities, gelling, reduced corrosion protection, and potential damage to the cooling system components. Always use genuine Subaru Super Coolant or an approved equivalent that specifically states compatibility with Subaru Super Coolant. Always dilute concentrated coolant with distilled water, not tap water, to prevent mineral deposits in the cooling system.

Transmission Fluid

The 2015 Subaru Forester was available with two transmission types: an automatic Continuously Variable Transmission (CVT) and a 6-speed manual transmission.

Continuously Variable Transmission (CVT)

For models equipped with the CVT, the specified fluid is Subaru CVTF-II. This is a highly specialized fluid designed specifically for Subaru's Lineartronic CVTs to ensure proper operation, durability, and efficiency.

Capacity: Approximately 13.0 US Quarts (initial fill for a dry transmission). A drain and refill typically uses less. Verify in your owner's manual.

Intervals: Subaru generally considers the CVT fluid as "lifetime" under normal driving conditions. However, for vehicles driven under severe conditions (e.g., heavy towing, mountainous driving, frequent stop-and-go traffic), an inspection and potential fluid change at 24,000–30,000 miles is often recommended by technicians to prolong the transmission's life. Always consult your owner's manual or a Subaru dealership for severe service recommendations.

Pitfalls: Only use genuine Subaru CVTF-II. Using any other type of automatic transmission fluid (ATF), including "universal" CVTF products, can lead to severe transmission damage, poor shifting performance, and reduced lifespan. The CVT is extremely sensitive to the correct fluid properties.

Manual Transmission

For models with the 6-speed manual transmission, the specified fluid is Subaru Extra MT 75W-90, which should meet API GL-5 specifications.

Capacity: Approximately 4.3 US Quarts.

Intervals: Manual transmission fluid typically has a longer service interval than engine oil. Subaru generally recommends inspection and replacement as needed, often around 30,000 miles for severe service or 60,000 miles for normal service. Consult your owner's manual.

Pitfalls: Ensure the fluid is rated API GL-5 to provide adequate protection for the gears. Using an incorrect viscosity or spec can lead to premature wear and difficult shifting.

Differential Fluid

Front Differential

The front differential on the 2015 Subaru Forester with a manual transmission shares its fluid with the manual transmission itself. Therefore, the same Subaru Extra MT 75W-90, API GL-5 fluid is used.

For CVT-equipped models, the front differential is integrated into the transmission case, and its lubrication is provided by the Subaru CVTF-II.

Capacity: Shared with the respective transmission.

Intervals: Shared with the respective transmission.

Pitfalls: Refer to the transmission fluid pitfalls. Using the wrong fluid for a CVT-equipped vehicle's front differential (which is effectively the CVT fluid) can damage the transmission.

Rear Differential

Both manual and CVT-equipped 2015 Forester models use 75W-90 gear oil meeting API GL-5 specifications for the rear differential.

Capacity: Approximately 0.8 US Quarts.

Intervals: Similar to manual transmission fluid, the rear differential fluid typically has a service interval around 30,000 miles for severe service or 60,000 miles for normal service. Always consult your owner's manual.

Pitfalls: While 75W-90 GL-5 is standard, ensure you are using a quality brand. Some limited-slip differentials (LSDs), though less common on this generation Forester, might require an LSD additive or a fluid designed for LSDs, but for the standard differential, a conventional GL-5 75W-90 is suitable. Check your specific vehicle's specifications if you suspect an aftermarket LSD may be installed.

Brake Fluid

The 2015 Subaru Forester requires DOT 3 or DOT 4 brake fluid. DOT 4 fluid has a higher wet and dry boiling point than DOT 3, offering slightly better performance, especially under demanding conditions. Both are glycol-ether based and are compatible.

Capacity: Varies depending on component replacement; consult service manual for specific bleeding procedures.

Intervals: Brake fluid is hygroscopic, meaning it absorbs moisture over time, which lowers its boiling point and can lead to corrosion in the braking system. Subaru generally recommends replacing brake fluid every 30,000 miles or 2 years, whichever comes first. This is a critical safety item.

Pitfalls: Never use DOT 5 (silicone-based) brake fluid in a system designed for DOT 3 or DOT 4. DOT 5 is not compatible and can severely damage the braking system seals. Always keep brake fluid containers sealed tightly as it absorbs moisture from the air. When topping off, use fluid from a freshly opened container. Do not mix DOT 3 and DOT 4 with DOT 5 fluids.

Power Steering Fluid

The 2015 Subaru Forester is equipped with an Electric Power Steering (EPS) system. Therefore, it does not use hydraulic power steering fluid. There is no power steering reservoir to check or fill.

Washer Fluid

Use any good quality, all-season windshield washer fluid suitable for your climate. Many formulations include antifreeze properties for winter use and bug/grime removers for summer.

Capacity: Approximately 1.3 US Quarts.

Intervals: Top off as needed.

Pitfalls: During winter months, ensure you use a washer fluid with adequate freeze protection to prevent the fluid from freezing in the reservoir, lines, or nozzles.

Diesel Exhaust Fluid (DEF)

The 2015 Subaru Forester is equipped with a gasoline engine and does not use Diesel Exhaust Fluid (DEF). DEF is only used in diesel vehicles with Selective Catalytic Reduction (SCR) systems.

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