The Complete Guide to Subaru Oil Filters: Selection, Replacement, and Maintenance​

The single most important thing you need to know about your Subaru’s oil filter is this: using the correct, high-quality filter and changing it at every oil service is non-negotiable for protecting your engine’s longevity, performance, and the signature reliability Subaru owners depend on. Neglecting this simple, inexpensive component can lead to accelerated engine wear, reduced fuel efficiency, and costly repairs that completely undermine the durable design of Subaru’s Boxer engines. This guide provides a definitive, practical resource for Subaru owners of all models—from Outback and Forester to WRX and Ascent—covering how to select the right filter, perform a proper replacement, and understand the critical role this part plays in your vehicle’s health.

​Understanding the Role of Your Subaru’s Oil Filter​

Engine oil is the lifeblood of your Subaru. It lubricates moving parts, reduces friction, cools engine components, and helps clean internal surfaces. However, as it circulates, it picks up microscopic contaminants. These include metal particles from normal engine wear, soot from combustion, tiny bits of rubber or plastic from aging seals, and external contaminants that can bypass the air filter. Without an effective filtration system, these abrasive particles would continuously recirculate, acting like sandpaper on precision-engineered components such as cylinder walls, camshafts, and bearing surfaces.

The ​Subaru oil filter​ is tasked with trapping and holding these harmful contaminants. It allows clean oil to flow freely to all critical engine parts. A failing or clogged filter can trigger a bypass valve, sending unfiltered oil into the engine, which is a protective but last-resort measure. Consistently using a filter designed for your specific engine’s flow rate, pressure, and capacity is paramount. For Subaru’s unique horizontally-opposed Boxer engine layout, which can have specific oiling needs and potential sludge concerns in some older models, maintaining pristine oil through a good filter is even more critical.

​Types of Oil Filters: Construction and Technology​

Not all oil filters are created equal. Understanding the basic construction helps you make an informed choice. The primary type used in modern Subarus is the spin-on filter, a self-contained metal canister that is screwed onto the engine block.

• ​Media Type:​​ The heart of the filter is the filtration media, usually a synthetic blend or microglass material pleated to maximize surface area. Higher-quality filters have more media with tighter, more consistent pore sizes to trap smaller particles without severely restricting oil flow.
• ​Anti-Drainback Valve:​​ This is a crucial feature, especially for Subaru engines where the filter is often mounted horizontally or at an angle. This rubber valve seals the filter’s inlet holes when the engine is off, preventing oil from draining out of the filter and back into the oil pan. This ensures immediate oil pressure upon startup, preventing a moment of critical dry operation. A faulty anti-drainback valve leads to noisy startups and increased wear.
• ​Bypass Valve:​​ A safety mechanism built into the filter. If the filter becomes completely clogged (e.g., from missed oil changes or extreme cold), this spring-loaded valve opens to allow oil to bypass the clogged media and still reach the engine. It prevents oil starvation, but the oil is unfiltered. ​This is not a feature to rely on; it is an emergency fail-safe.​​
• ​End Discs and Sealing Gasket:​​ The media is sealed at the top and bottom by metal or composite end discs. The critical rubber gasket on the top of the filter provides the seal against the engine block. High-quality gasket material resists cracking, heat degradation, and ensures a leak-free installation.

​Choosing the Right Oil Filter for Your Subaru​

Selecting the correct filter is not a matter of guesswork. Using the wrong filter can lead to leaks, poor filtration, or oil pressure issues.

1. ​Consult Your Owner’s Manual:​​ This is the definitive source. It will specify the exact part number or filter specifications required for your model year, engine, and sometimes even production date.
2. ​OEM vs. Aftermarket:​​ Genuine ​Subaru OEM oil filters​ are engineered specifically for your vehicle. They are designed to meet the exact flow, pressure, and capacity requirements of your engine. They consistently feature high-quality anti-drainback valves and correct bypass valve pressure settings. Aftermarket brands (like Fram, Wix, Bosch, Purolator, K&N) offer varying levels of quality. Some are excellent and may offer premium synthetic media options. The key is to choose a reputable brand’s premium line, not their most basic economy filter.
3. ​Part Number Cross-Reference:​​ Common genuine Subaru part numbers include 15208AA15A, 15208AA12A, and 15208AA160, but these vary by model. Always verify. Many aftermarket boxes will list which Subaru models their filter fits.
4. ​Special Considerations:​​
   • ​High-Performance Models (WRX/STI):​​ These turbocharged engines operate under higher stress, temperatures, and oil pressure. Using a high-quality filter, often with a robust synthetic media, is strongly advised. Some owners opt for filters from manufacturers like Tokyo Roki (the OEM supplier) or premium aftermarket lines.
   • ​Newer vs. Older Subarus:​​ Newer Direct Injection (DIT) turbo engines and older naturally aspirated engines have different contaminant profiles. Modern filters are designed to handle the specific soot and fuel dilution challenges of newer engines.
   • ​Extended Oil Change Intervals:​​ If you use high-quality synthetic oil and follow a longer service interval (always within Subaru’s recommendations, often found in the manual for “severe” vs. “normal” conditions), a filter with high-capacity, high-efficiency media is essential to last the entire interval.

​Step-by-Step: Replacing Your Subaru Oil Filter​

Performing an oil and filter change is a common DIY task for Subaru owners. Here is a safe, methodical procedure.

​Tools and Materials Needed:​​

• Correct amount and grade of engine oil (e.g., 0W-20, 5W-30 – see manual)
• Correct new ​Subaru oil filter​
• Oil filter wrench (cap-style or strap wrench)
• Socket wrench set, ratchet, and correct size socket for drain plug (often 17mm or 14mm)
• Drain pan (at least 6-quart capacity)
• Funnel
• Gloves and safety glasses
• Rags or paper towels
• Jack and jack stands or vehicle ramps (ensure the vehicle is level for complete drainage)
• New drain plug washer (crush washer) – highly recommended

​Procedure:​​

1. ​Preparation:​​ Run the engine for a few minutes to warm the oil (not hot). This thins the oil for more complete drainage. Park on a level surface, engage the parking brake, and chock the rear wheels. Safely lift the front of the vehicle and support it with jack stands. Never work under a vehicle supported only by a jack.
2. ​Drain Old Oil:​​ Place the drain pan under the oil pan. Using the socket, loosen the drain plug. Carefully finish unscrewing it by hand, pushing it away from you as the final threads release to avoid the hot oil stream. Allow the oil to drain completely. Clean the drain plug and replace the crush washer. Reinstall and tighten the plug to the manufacturer’s torque specification (if known) or snugly—avoid overtightening.
3. ​Remove Old Oil Filter:​​ Move the drain pan under the filter. The filter’s location varies: on many Subarus (like the 2.5L FB/FA series), it’s located on top of the engine near the intake manifold, accessible from the top. On older EJ series engines, it’s typically on the bottom near the headers. Use the oil filter wrench to loosen the filter. Once loose, unscrew it by hand. Be prepared for oil to spill from the filter. Tip the open end up as you remove it to minimize spillage. Wipe clean the filter mounting surface on the engine block.
4. ​Install New Oil Filter:​​ Dip your finger in clean new oil and lightly coat the rubber gasket on the top of the new ​Subaru oil filter. This ensures a proper seal and prevents the gasket from tearing or binding during installation. Screw the filter onto the engine by hand until the gasket makes contact with the sealing surface. Then, tighten it an additional ¾ to 1 turn by hand only. ​**Do not use a wrench to overtighten the filter;**​ hand-tight is sufficient and prevents damage.
5. ​Add New Oil:​​ Locate the oil fill cap on top of the engine. Use a funnel to pour in the specified amount and type of new oil. Refer to your manual for capacity; it’s usually between 5.1 to 5.4 quarts for a 4-cylinder with filter change, but verify. Do not overfill.
6. ​Check for Leaks and Final Steps:​​ Reinstall the oil fill cap. Start the engine and let it run for about 30 seconds. The oil pressure light may stay on for a few seconds—this is normal as the new filter fills. Carefully look under the vehicle at the drain plug and around the filter for any signs of leaks. Turn off the engine, wait a minute, and check the dipstick. Add small amounts of oil if needed to bring the level to the full mark. Properly dispose of the used oil and filter at a recycling center or auto parts store.

​Common Questions and Troubleshooting​

• ​How often should I change my Subaru oil filter?​​ Always change the filter with every oil change. Subaru’s standard oil change interval is typically 6,000 miles or 6 months under normal conditions, but consult your specific manual. Severe driving conditions (short trips, extreme temperatures, towing, dusty environments) warrant more frequent changes.
• ​Can I use any brand that says it “fits”?​​ While it may physically screw on, it may not have the correct internal specifications. Stick with known quality brands or OEM. The few dollars saved on a cheap, no-name filter is not worth the risk.
• ​My filter is leaking. What happened?​​ The most common causes are: a doubled-up old gasket left on the engine block, an improperly lubricated or damaged new gasket, or overtightening/under-tightening of the filter. Always ensure the old gasket came off and the new one is lightly oiled and hand-tight.
• ​The oil pressure warning light flickers at idle. Is it the filter?​​ A severely clogged filter can restrict flow and cause low oil pressure, especially at low RPM. However, this symptom could also indicate other serious issues like a failing oil pump or low oil level. Check the oil level and condition immediately. If you just changed the filter, ensure the correct one was used.
• ​Are reusable filters a good option for Subarus?​​ While some enthusiasts use high-end reusable metal can filters, they require meticulous cleaning and re-oiling of the internal media element. For most owners, the convenience, guaranteed seal, and consistent performance of a new, quality spin-on filter make it the better choice.

​The Impact of Neglect and the Long-Term View​

Consistently using a high-quality ​Subaru oil filter​ is one of the easiest and most cost-effective forms of preventative maintenance. Over time, clean oil minimizes wear on:

• ​Turbocharger bearings​ (in applicable models), which spin at extremely high speeds and are sensitive to oil quality.
• ​Variable Valve Timing (AVCS) solenoids and components,​​ which rely on clean oil for precise operation.
• ​Piston rings and cylinder walls,​​ ensuring proper compression and preventing oil consumption.
• ​All bearing surfaces,​​ preserving engine performance and efficiency.

Skipping a filter change or using a subpar filter introduces abrasive particles into this tightly toleranced system. The damage is cumulative and often not apparent until it manifests as reduced power, engine noise, increased oil consumption, or catastrophic failure.

​Final Recommendation​

For the vast majority of Subaru owners, the simplest and most reliable path is to use a ​genuine Subaru OEM oil filter​ purchased from a dealership or reputable online source. It guarantees compatibility and performance. For those who prefer aftermarket, select a premium filter from a top-tier brand like Wix (XP series), Mobil 1, or PurolatorONE. Pair this with a quality synthetic or synthetic-blend oil that meets the API SP and ILSAC GF-6 standards (or the specific standard listed in your manual). Keep a record of your services, and never underestimate the importance of this small, cylindrical component. Your Subaru’s signature symmetrical all-wheel-drive system and Boxer engine are designed for the long haul; protecting them starts with clean oil and a dependable filter at every single service interval.