The 2008 Mercedes-Benz CL550 is a high-performance luxury coupe powered by a robust 5.5L V8 engine, known as the M273. To keep this sophisticated vehicle running smoothly and to ensure its longevity, it is essential to use lubricants that meet or exceed the stringent German engineering standards. Using the correct fluids reduces internal friction, manages the extreme heat generated by the engine and transmission, and protects critical components from wear and corrosion. AMSOIL synthetic lubricants are formulated to provide superior protection for European vehicles, offering extended drain intervals and enhanced performance in both extreme heat and cold conditions.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – Specifically engineered with a European formula to meet the precise requirements of the 2008 CL550’s V8 engine, providing excellent high-temperature stability.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An ideal choice for extreme cold starting conditions while maintaining essential viscosity at operating temperature for the Mercedes M273 engine.
- AMSOIL Oil Filter – Features premium media to capture microscopic wear-causing contaminants, helping to maximize engine life and reduce wear in the CL550.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Designed to withstand the rigors of the 722.9 transmission, offering protection against heavy towing, elevated temperatures, and challenging terrain.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective option that provides OE-equivalent protection for the automatic transmission, reducing wear and extending service life.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol-based pre-mix that provides protection up to 150,000 miles or 5 years, safeguarding all cooling system metals and hoses.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Delivers excellent ABS and traction-control responsiveness with a stable viscosity over a wide temperature range, suitable for Mercedes brake systems requiring DOT 4 plus standards.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Reduces friction and helps seals remain soft to prevent leaks, ensuring quiet operation and long fluid life for the power steering system.
- AMSOIL P.i.® Performance Improver Gasoline Additive – Restores lost horsepower and cleans GDI fuel injectors, improving fuel economy and ensuring the engine runs at peak efficiency.
Engine Oil and Filtration
The heart of the 2008 Mercedes-Benz CL550 is its 5.5L 8-cylinder engine, identified by engine code 273.961 4. This powerful V8 requires motor oil that can handle high stress and maintain film strength under heavy loads. For this vehicle, AMSOIL offers two primary European-specific formulations: the 5W-40 FS and the 0W-40 FS. Both are 100% synthetic oils designed with a precise blend of base oils and premium additives to meet the unique demands of European gasoline and diesel engines.
The oil capacity for the engine is 9.0 quarts when performing a standard oil change with a filter replacement. It is important to note that on models equipped with an oil cooler, additional oil may be required if the cooler is drained during the service. After refilling, it is recommended to allow approximately 5 minutes to pass before checking the oil level, whether with the engine off or running, to ensure an accurate reading. When installing the drain plug, a torque of 22 ft/lbs should be applied to ensure a proper seal without damaging the threads.
For filtration, the system relies on a high-quality oil filter to keep the oil clean. The AMSOIL Oil Filter (Code EA15K39-EA) is a direct recommendation, offering filtering efficiency of 99 percent at 20 microns. It provides greater capacity for contaminants than competing filters, which helps reduce engine wear and extends the service life of the oil. If you prefer an aftermarket alternative that is widely available, the WIX Oil Filter (Code 57078-EA) or the MANN-FILTERS Oil Filter (Code HU7185X-EA) are also suitable options that offer premium media improvements over standard OEM-branded filters. Additionally, keeping the engine breathing properly is crucial; the MANN-FILTERS Air Filter (Code C369832-EA) is recommended to ensure optimal airflow and combustion efficiency.
Transmission and Cooling Systems
The transmission system in the CL550, specifically the 722.9 automatic transmission, demands a fluid that can manage high thermal loads and provide smooth shifting. Whether your vehicle has the A89 code (Reduced-Friction) or not, the total fill capacity for a 7-speed 722.9 transmission is 10.4 quarts. AMSOIL provides two top-tier synthetic automatic transmission fluids to meet these needs. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to withstand heavy towing, elevated temperatures, and challenging terrain. It remains fluid even in sub-zero temperatures, providing reserve protection during heavy use. The AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid offers a slightly more budget-friendly option that still delivers OE-equivalent protection against wear and temperature-related issues.
Maintaining the cooling system is vital for a high-performance engine like the M273. The cooling capacity of the system is approximately 12.7 quarts. Using the correct antifreeze and coolant prevents corrosion, freezing, and overheating. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a phosphate-, nitrate-, nitrite-, silicate-, borate-, and amine-free formula that is compatible with all other antifreeze colors. It offers protection up to 150,000 miles or 5 years. For those who prefer a concentrated fluid that requires mixing with distilled water, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant is an excellent choice. It offers superior protection, capable of lasting up to 150,000 miles in passenger cars or even longer in heavy-duty applications.
Brake, Steering, and Performance Additives
Safety and control are paramount for a luxury coupe. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid meets the requirement for the CL550 (Model HBH), which calls for a DOT 4 plus fluid, or one approved on the MB Sheet 331.0 standard. It provides stable viscosity across a wide temperature range and ensures excellent responsiveness for the ABS and traction control systems.
Power steering in the CL550 benefits from a synthetic fluid that resists heat and maintains seal integrity. The AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid reduces friction, helps seals stay soft to prevent leaks, and resists heat for long fluid life. It is formulated for quiet operation, which contributes to the refined driving experience expected of the CL550.
To further enhance engine performance and fuel economy, the AMSOIL P.i.® Performance Improver is highly recommended. This gasoline additive helps restore up to 14% horsepower and cleans GDI fuel injectors to a 100% flow rate after just one tank of fuel. It also helps prevent carbon buildup and reduces the need for higher-octane fuel, ensuring your 2008 CL550 performs at its peak efficiency.
Vehicle Background
About the 2008 Mercedes-Benz CL550
The 2008 Mercedes-Benz CL550 represents the pinnacle of Mercedes-Benz luxury coupe design from the early 2000s. Part of the second generation (C216) of the CL-Class, which debuted as a 2007 model year vehicle to replace the S-Class-based CL-Class, the CL550 was built to offer a blend of grand touring capability and coupe styling. The platform shares its underpinnings with the S-Class sedan, ensuring a high level of refinement, safety, and ride comfort.
Under the hood, the CL550 is powered by the 5.5-liter M273 V8 engine. This naturally aspirated V8 produces a substantial amount of power and torque, delivering smooth acceleration that characterizes the Mercedes driving experience. The engine is known for its robust construction and relatively smooth operation, though like many high-performance German engines of this era, it benefits greatly from regular maintenance using high-quality synthetic lubricants. The CL550 was positioned as a sophisticated alternative to the BMW 7 Series-based coupe counterparts, appealing to drivers who wanted a more agile and sporty presence than the S-Class sedan offered, without sacrificing the luxury amenities associated with the brand.
Owners of the CL550 often appreciate its balanced handling, luxurious interior appointments, and the prestige of the Mercedes badge. The vehicle is designed for long-distance comfort and high-speed stability, making it an ideal candidate for extended road trips. However, to maintain this level of performance over the years, owners must pay close attention to fluid quality. Using the correct AMSOIL products ensures that the engine, transmission, and ancillary systems remain in optimal condition, preserving the vehicle’s value and driving dynamics for years to come. The CL550 is a vehicle that demands respect through proper care, and utilizing synthetic lubricants is a critical component of that care.