Maintaining the 2004 Mercedes-Benz C240 with its 2.6L inline-six engine requires a dedication to precise fluid specifications. This German-engineered sedan was designed for a balance of luxury and performance, utilizing the robust M112 engine code 112.912.1. Keeping the internal components lubricated with the correct synthetic fluids is essential for longevity, ensuring that the vehicle continues to deliver smooth power delivery and reliable handling for years to come. The engine’s tolerance for heat and friction demands a fluid that can withstand the rigors of daily driving as well as high-load conditions.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A specialized synthetic formula designed for the unique thermal and wear demands of European gasoline, diesel, and hybrid vehicles, providing superior protection for the M112 engine.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An ultra-low temperature option that ensures rapid oil flow during cold starts while maintaining a strong lubricating film at high operating temperatures.
- AMSOIL Oil Filter – Engineered with premium media to capture 99 percent of wear-causing contaminants at 20 microns, extending the life of the synthetic oil and the engine itself.
- WIX Oil Filter – A premium aftermarket option featuring media that offers improvements over original equipment manufacturer branded filters for high-flow efficiency.
- MANN-FILTERS Oil Filter – A factory-spec replacement featuring premium filtration media to protect the engine from particulate buildup.
- MANN-FILTERS Air Filters – Premium media improvements over original equipment manufacturer branded filters ensure clean air for optimal combustion.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A ready-to-use 50/50 pre-mix formulation that protects all cooling system metals, gaskets, and hoses for up to 150,000 miles.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – Concentrated coolant that offers extended protection for up to 150,000 miles when mixed with distilled water.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Withstands the rigors of the 5-speed automatic transmission, remaining fluid in extreme temperatures and providing reserve protection during heavy use.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A fuel-efficient option that protects against wear in automatic transmissions.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Delivers excellent ABS and traction-control responsiveness with a stable viscosity range that resists moisture absorption and boiling.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Formulated to reduce friction, prevent leaks by keeping seals soft, and resist heat for extended fluid life in the steering system.
- AMSOIL Gasoline Stabilizer – Helps keep fuel fresh for up to 12 months, fighting ethanol corrosion and preventing gum buildup.
- AMSOIL Engine Fogging Oil – Highly-effective rust preventive designed to protect internal engine components during storage or long periods of inactivity.
- AMSOIL P.i. Performance Improver Gasoline Additive – Restores up to 14% horsepower and improves fuel economy.
- AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor – Lubricates fuel system and upper cylinders.
- AMSOIL Synthetic Multi-Purpose Grease – Resists thermal and oxidation degradation for long-term performance.
- AMSOIL Heavy-Duty Metal Protector – Protects against the effects of salt, moisture and chemical corrosion.
- AMSOIL MP Metal Protector – Cuts through rust and frees frozen components.
- AMSOIL Silicone Spray – Protects with a dry lubricating film ideal for surfaces that may be damaged by conventional lubricants.
- AMSOIL Heavy-Duty Degreaser – Dissolves oil, tar and grime.
- AMSOIL Power Foam Carburetor and Induction-System Cleaner – Cleans deposits from ethanol and degraded fuel.
- AMSOIL Miracle Wash Waterless Wash and Wax Spray – Requires just two easy steps and leaves vehicles with a fantastic shine.
- AMSOIL Brake and Parts Cleaner – Quickly removes oil, grease, brake fluid and other contaminants.
- AMSOIL Mudslinger Mud and Dirt Repellent – Provides a protective, non-stick layer of armor against the accumulation of mud, dirt and snow.
- AMSOIL Engine Degreaser – Professional-strength formula that quickly removes the toughest grease and grime.
- AMSOIL Glass Cleaner – Effectively cuts through grease and grime faster than other leading glass cleaners.
- AMSOIL High-Foam Car Shampoo – Hard on dirt, gentle on coatings and finishes.
- AMSOIL Exterior Ceramic Spray – Sheds water rapidly and protects against UV rays.
- AMSOIL Interior Detailer – Light Lemon – Multi-surface use with 90-day UV protection.
- AMSOIL Interior Detailer – Scent Free – Multi-surface use with 90-day UV protection.
The 2004 Mercedes-Benz C240 is powered by the 2.6-liter M112 inline-six engine, a unit renowned for its smooth power delivery and durability. With a recommended oil capacity of 7.9 quarts including the filter change, selecting the correct viscosity and filter combination is critical for optimal performance. The M112 series engines require fluids that can handle the specific demands of European design, where precision machining and tight tolerances make the difference between a smooth-running engine and one plagued by premature wear. Synthetic motor oils provide a distinct advantage here, offering superior thermal stability compared to conventional oils, which is vital for the C240’s high-performance potential and longevity.
Engine Oil and Filtration Specifications
Proper lubrication begins with the engine oil. For this vehicle, AMSOIL recommends two primary viscosities depending on your climate and driving habits. The 5W-40 FS 100% Synthetic European Motor Oil is formulated specifically for the unique demands of gasoline, diesel, and hybrid European vehicles. It features a precise blend of synthetic base oils and premium additives that reduce wear and maintain engine cleanliness. If you operate in colder climates or prefer maximum flow during winter startup, the 0W-40 FS 100% Synthetic European Motor Oil is an excellent alternative. Both options are designed to exceed industry standards for protection against high temperatures and friction.
Equally important is the oil filter used during these changes. The AMSOIL Oil Filter is designed to provide filtering efficiency of 99 percent at 20 microns, allowing lower restriction to keep engine parts lubricated. It offers greater capacity for small, wear-causing contaminants than competing filters, which helps reduce engine wear over extended intervals. For those preferring a specific aftermarket brand, the WIX Oil Filter and the MANN-FILTERS Oil Filter are also recommended options, both offering premium media improvements over standard OEM-branded filters.
When servicing the engine, it is crucial to respect the manufacturer’s torque specifications. The oil drain plug should be torqued to 27 ft/lbs. Additionally, owners should allow 5 minutes after refilling or turning the engine off before checking the oil level to ensure an accurate reading. On models equipped with an oil cooler, it is worth noting that additional oil may be needed when the cooler is drained during service.
Transmission and Cooling System Fluids
The transmission in the 2004 C240, specifically the 5-speed automatic (722.6), requires a fluid that can handle elevated temperatures and the rigors of shifting. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is engineered to withstand heavy towing, elevated temperatures, and challenging terrain while remaining fluid in sub-zero conditions. This fluid provides reserve protection during heavy use, ensuring smooth shifts and reducing the risk of sludge formation. A total fill for the transmission requires 8.5 quarts, so owners planning a complete flush should account for this volume. Alternatively, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid offers protection against wear.
The cooling system is equally vital for this engine. The radiator holds 11.1 quarts of fluid. Using a high-quality antifreeze is essential to prevent overheating and corrosion. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a phosphate-, nitrate-, and silicate-free formulation that protects all cooling system metals, gaskets, and hoses. It is a 50/50 pre-mix that offers protection for up to 150,000 miles or 5 years. For those who prefer concentrated coolants, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant can be mixed with distilled water, offering extended protection for up to 150,000 miles or 5 years in passenger cars.
Brake and Steering Fluids
Braking safety and steering responsiveness are paramount for a vehicle of this caliber. The 2004 C240 requires brake fluid that meets MB Sheet 331.0 specifications, such as DOT 4 plus. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent ABS and traction-control responsiveness. It maintains a stable viscosity over a wide temperature range, preventing the brake fade that can occur with standard fluids under hard driving conditions.
Similarly, the power steering system benefits from a synthetic fluid that resists heat and keeps seals in peak condition. The AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid reduces friction and helps seals remain soft to prevent leaks. Its strong anti-wear protection and excellent high-temperature performance ensure that the steering remains quiet and responsive throughout the life of the fluid.
Additional Maintenance and Care
Beyond the essential fluids, regular maintenance includes attention to the air filtration system. The MANN-FILTERS Air Filters provide premium media improvements over original equipment manufacturer branded filters, ensuring clean air enters the engine for optimal combustion. For seasonal storage or vehicles that sit for extended periods, AMSOIL Gasoline Stabilizer helps keep fuel fresh for up to 12 months, fighting ethanol corrosion and preventing gum buildup.
Engineers have designed the C240 to be a refined driver’s car, and the right maintenance routine respects that heritage. By using these specialized fluids, owners can ensure the vehicle continues to perform as intended. The combination of synthetic oils, high-quality filters, and durable transmission fluids creates a protective environment for the mechanical components, reducing the risk of costly repairs and maintaining the vehicle’s value.
Model History and Performance
The 2004 Mercedes-Benz C240 represents a significant era in the C-Class lineup, built on the W203 chassis. This generation was the first C-Class to be designed as a global vehicle, meaning it was engineered to meet safety and performance standards in every market where it was sold. Powered by the M112 2.6-liter inline-six engine, the C240 delivered approximately 168 horsepower, providing a smooth and linear power curve that was characteristic of Mercedes-Benz engines of that period.
Owners of the W203 C240 often appreciate the driving dynamics, which blend the comfort expected of a luxury sedan with a handling balance that encourages spirited driving. The independent suspension on all four wheels contributes to a composed ride, while the hydraulic power steering offers a tactile connection to the road that many enthusiasts value. The 2.6L engine, known for its reliability, pairs well with the five-speed automatic transmission, offering a seamless transition through gears.
This model was marketed as a practical yet stylish choice for professionals and families alike. The interior design emphasized ergonomics and quality materials, with a dashboard layout that was intuitive for the driver. Over the years, the C240 has developed a reputation as a durable vehicle, provided it receives consistent maintenance. The robust nature of the M112 engine allows it to handle high mileage with proper care, making it a popular choice for those seeking a reliable German sedan without the complexity of later turbocharged models.
Maintenance of the C240 is not just about keeping the car running; it is about preserving the driving experience. Regular fluid changes, using products specifically suited for European engineering, ensure that the engine’s smoothness and the transmission’s shift quality remain consistent. Whether commuting daily or enjoying a weekend drive, the C240 remains a rewarding vehicle when supported by high-quality lubricants and filters.