Maintaining the 2008 Subaru Forester with the 2.5L EJ255E turbocharged engine requires strict adherence to lubrication schedules, particularly because of a known factory concern regarding oil starvation in early turbo models. Proper fluid selection is not merely about filling a reservoir; it is about preventing catastrophic failure of the turbocharger and ensuring the boxer engine runs smoothly under load. For owners of this vehicle, using high-quality synthetic lubricants designed to withstand extreme temperatures and protect against premature wear is essential for longevity.
Recommended AMSOIL Products
To address the specific needs of the 2008 Subaru Forester, including its turbocharged engine and all-wheel-drive system, the following AMSOIL products provide superior protection compared to standard conventional oils. These selections are optimized for the 5W-30 viscosity required by this engine and include compatible WIX Air Filter and WIX Oil Filter for a complete maintenance solution.
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – Offers the highest level of protection against horsepower loss and wear, ideal for the turbocharged 2008 Forester.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – Provides extended protection up to 20,000 miles with enhanced cleaning power to keep the engine running smoother.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – A cost-effective option that fights sludge and deposits while protecting turbochargers effectively.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Formulated specifically for engines with over 75,000 miles to reduce sludge and improve performance.
- AMSOIL Oil Filter – Delivers 99% filtering efficiency at 20 microns to remove small, wear-causing contaminants that harm the engine.
- WIX Oil Filter – A premium aftermarket option that offers media improvements over original equipment manufacturer-branded filters.
- WIX Air Filter – Ensures clean airflow to the turbocharged engine with premium filtration media.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A pre-mixed solution protecting all cooling system metals, gaskets, and hoses for up to 150,000 miles.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option for maximum longevity in passenger cars and light trucks.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Withstands heavy towing and high temperatures while remaining fluid in sub-zero conditions.
- AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Promotes smooth, shudder-free shifts and guards against leaks.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Provides advanced protection against wear and rust, suitable for various manual transmissions and limited-slip differentials.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Ideal for front and rear differentials and manual transmissions, controlling thermal runaway and reducing operating temperatures.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – A heavier viscosity option for manual transmissions and differentials requiring robust protection.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures excellent ABS and traction-control responsiveness with stable viscosity across a wide temperature range.
Addressing Turbocharger and Oil Interval Concerns
Owners of the 2008 Subaru Forester with the 2.5L turbocharged engine must be aware of a specific factory design issue. Subaru issued Service Bulletin #02-103-07, identifying a premature clogging problem with the oil mesh screen inside the oiling system that supplies the turbocharger. If this screen becomes clogged, it leads to oil starvation, which can result in catastrophic turbocharger failure. In response, Subaru published Service Bulletin #02-110-10R, which updated the recommended maintenance intervals for 2010 model year and earlier turbocharged engines.
Under these guidelines, owners are advised to change the oil and filter every 3,750 miles or 3 3/4 months, rather than following standard extended intervals. While AMSOIL Signature Series 5W-30 synthetic motor oils offer superior stability and resistance to breakdown, allowing for potential extended drain intervals on many vehicles, the specific design flaw in this Subaru engine necessitates a return to stricter adherence to these manufacturer-recommended drain intervals. By following this schedule, you mitigate the risk of clogged screens. Furthermore, using a high-quality synthetic oil like the AMSOIL Signature Series 5W-30 provides enhanced protection against the harsh conditions the turbocharger endures, ensuring that even within the conservative 3,750-mile window, the engine receives maximum protection.
The recommended oil viscosity for all temperatures is 5W-30. While the engine can operate on 10W-30 or 10W-40 above -20°C, 5W-30 is preferred for year-round operation. The total oil capacity, including a filter change, is 4.4 quarts. When performing the oil change, ensure the drain plug is torqued to 33 ft/lbs. It is crucial to check the oil level after refilling to guarantee proper lubrication levels.
Engine Protection and Oil Filter Selection
The Subaru EJ255E is a horizontally opposed (boxer) four-cylinder engine, a design that presents unique lubrication challenges due to its layout. When the vehicle is tilted or cornered, oil can pool in one side of the crankcase, potentially starving the oil pump momentarily. AMSOIL Extended-Life 5W-30 motor oil is formulated to maintain a stable film of oil on critical components, reducing the risk of wear during these moments. Additionally, the high-velocity turbulence created by the turbocharger demands an oil with excellent thermal stability and resistance to coking.
A high-efficiency AMSOIL Oil Filter is just as critical as the oil itself. The AMSOIL Oil Filter is designed to capture 99% of contaminants at 20 microns, which is smaller than the particles that standard filters catch. This is vital for the turbocharger, as any debris circulating in the oil can score the delicate bearings. The filter also offers greater capacity for small wear-causing contaminants, extending the life of the oil and the engine. For those seeking a reliable aftermarket alternative, the WIX Oil Filter provides premium media that outperforms many OEM-branded filters.
Complete Fluid Maintenance for Transmission and Differentials
The 2008 Forester’s all-wheel-drive system relies on a complex network of transmissions and differentials that require precise lubrication. For automatic transmission applications, the fluid capacity is 9.8 quarts for a total fill in the 4-speed model. Using a premium fluid like the AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid ensures the transmission remains fluid in sub-zero temperatures and resists the high heat generated during towing or driving in challenging terrain. This fluid helps prevent the shudder and slipping that can occur with older transmission fluids.
For manual transmissions, the fluid capacity is 7.4 pints. The AMSOIL SEVERE GEAR® 75W-90 is an excellent choice here, as it contains friction modifiers beneficial for limited-slip differentials and helps control thermal runaway. The Subaru Forester features both front and rear differentials; the front capacity is 2.5 pints, and the rear is 1.7 pints. In both cases, 75W-90 synthetic gear lube is recommended to protect against rust, corrosion, and wear. For applications requiring slightly higher viscosity, the AMSOIL SEVERE GEAR® 80W-90 or the AMSOIL SEVERE GEAR® 75W-110 are suitable alternatives that provide long oil, seal, and equipment life.
Cooling System and Brake Fluid Performance
Maintaining the cooling system is critical for the 2008 Forester, especially given the high operating temperatures of the turbocharged engine. The total coolant capacity varies by transmission type: 7.8 quarts with the MTXL transmission and 7.7 quarts with the ATXL transmission. A pre-mixed antifreeze like the AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is engineered to protect all cooling system metals, gaskets, and hoses. It is phosphate-, nitrate-, nitrite-, silicate-, borate-, and amine-free, ensuring compatibility with all other antifreeze colors and extending protection up to 150,000 miles or 5 years.
For safety and responsiveness, the hydraulic brake system requires a fluid that maintains stability under the extreme heat generated during braking. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent ABS and traction-control responsiveness. Unlike conventional brake fluids that can absorb moisture over time and lower the boiling point, this synthetic fluid resists water contamination, ensuring consistent pedal feel and stopping power in all weather conditions.
About the Vehicle: 2008 Subaru Forester
The 2008 Subaru Forester is a compact crossover SUV that stands out in the automotive landscape for its distinctive design and practical utility. Based on the Subaru Impreza platform, the Forester features Subaru’s signature Symmetrical All-Wheel Drive system, which provides superior traction and handling stability in various road conditions, from dry highways to snowy mountain passes. The 2.5L 4-cylinder engine code EJ255E mentioned in this guide is the turbocharged variant, part of Subaru’s legacy of boxer engines known for their low center of gravity and smooth power delivery.
Subaru introduced the “S” trim for the 2008 model year, which brought significant updates to the interior and exterior, making the vehicle more rugged and modern. The Forester is highly regarded by owners for its boxy, upright design, which maximizes cargo space and visibility. This practicality, combined with Subaru’s reputation for building durable, long-lasting vehicles, has made the Forester a favorite among outdoor enthusiasts and families. The 2008 model year sits at a point where the design is robust yet refined, representing a popular era for the brand in the North American market.
While the turbocharged models offer spirited performance with quick acceleration, the standard naturally aspirated versions provide a reliable and efficient daily driving experience. The vehicle’s ground clearance and all-wheel-drive capabilities make it versatile for light off-roading, trail driving, or simply navigating winter snowstorms with confidence. Understanding the specific maintenance needs of this unique engineering is key to keeping it running reliably for years to come.