The 2008 Mercedes-Benz CLS550 is a sophisticated grand tourer that blends the sleek, four-door coupe styling with the power of a 5.5-liter V8 engine. Maintaining this unique vehicle requires lubricants that meet rigorous European specifications. The engine, designated as code 273.960 6, operates under high thermal loads and demands a fluid that can withstand extreme temperatures while providing maximum protection to critical internal components. Using the correct oil grade, a high-efficiency filter, and compatible fluids for the transmission and cooling system is essential for preserving the vehicle’s performance, fuel economy, and longevity. Neglecting specific lubrication requirements can lead to reduced efficiency, increased wear, and costly repairs on this German engineering masterpiece.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A specialized formula designed specifically for the demanding thermal and friction requirements of European gasoline, diesel, and hybrid vehicles, featuring a precise blend of synthetic base oils and premium additives.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – Offers superior cold-start protection and high-temperature stability, engineered to meet the exacting standards of European manufacturers for optimal engine performance.
- AMSOIL Oil Filter – Delivers 99% filtering efficiency at 20 microns, providing greater capacity for small contaminants and lower restriction to keep engine parts properly lubricated with extended service life.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A unique poly-organic acid (OAT) formulation that protects all cooling system metals and hoses, offering service intervals up to 150,000 miles or 5 years without phosphates or silicates.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that can be mixed with distilled water to provide exceptional corrosion protection and extend service life up to 1,000,000 miles in certain applications.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Withstands the rigors of heavy towing and elevated temperatures, remaining fluid in sub-zero conditions to protect the transmission from wear and sludge.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective yet high-performance alternative designed to protect against wear and maintain fluid efficiency for European automatic transmissions.
Engine Oil and Filtration Requirements
Proper lubrication begins with the engine oil. The 2008 Mercedes-Benz CLS550 with the 5.5L V8 (Engine Code 273.960 6) requires a specific viscosity to ensure optimal flow across a range of temperatures. The engine capacity is 9.0 quarts when including a filter change, so after refilling, it is critical to check the oil level to ensure accuracy. AMSOIL offers two distinct options for this vehicle, both formulated to exceed the requirements of European vehicles.
The AMSOIL 5W-40 FS 100% Synthetic European Motor Oil is an excellent choice for year-round use or warmer climates. Its 5W rating ensures easy cold starts, while the 40 weight provides a robust lubricating film at operating temperature. This fluid is designed specifically for the precise tolerances found in European engines. Alternatively, the AMSOIL 0W-40 FS 100% Synthetic European Motor Oil offers the highest level of cold-flow performance, making it ideal for vehicles frequently operated in extremely cold environments. Both products feature a premium additive package that controls varnish and sludge, ensuring the engine remains clean internally. This is particularly important for the high-output M273 engine, which benefits from the superior thermal stability of synthetic fluids.
Filtration is equally vital. The standard oil change requires a filter capable of handling the specific flow rates and particle sizes common in this engine. The AMSOIL Oil Filter is engineered to remove 99% of harmful contaminants at 20 microns. By allowing for lower restriction than standard filters, it maintains a steady flow of clean oil to the bearings and camshafts, reducing wear over the long term. For those who prefer OEM-brand parts, the WIX Oil Filter is also a recommended alternative, offering premium media that improves upon original equipment specifications.
Transmission Fluid and Cooling System Care
The automatic transmission in the CLS550 is a complex component that demands high-quality fluid to function correctly. For the 722.9 transmission (without code A89), the total fill capacity is approximately 9.7 quarts. Using a dedicated synthetic transmission fluid is key to ensuring smooth shifts and protecting against heat-induced degradation. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to withstand the extreme heat and load cycles associated with this performance sedan. It helps maintain fluid viscosity and prevents the breakdown that leads to sludge and clutch wear.
Alternatively, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid provides reliable protection and fuel economy benefits without compromising on the durability required for European automatic transmissions. These fluids ensure that the transmission remains responsive and protected, even under the stress of spirited driving or heavy towing.
The cooling system also plays a pivotal role in the longevity of this vehicle. With a capacity of 11.9 quarts, the cooling system requires a fluid that offers robust corrosion protection for aluminum and steel components. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a 50/50 pre-mix formulation that is phosphate-free, silicate-free, and nitrite-free. This compatibility ensures it works safely with all cooling system metals and hoses, preventing corrosion and cavitation. For those who prefer a concentrated coolant that offers maximum service life, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant provides exceptional protection against metallic corrosion and erosion, extending the life of the cooling system components.
Maintenance and Vehicle Care
Beyond fluids, keeping the 2008 Mercedes-Benz CLS550 in top condition involves proper fuel system maintenance and exterior protection. The vehicle benefits from the use of a fuel system cleaner to restore injector performance and maintain optimal fuel economy. Additionally, for seasonal storage, preventing fuel degradation and internal corrosion is vital. Products such as AMSOIL Gasoline Stabilizer can help keep fuel fresh, while AMSOIL Engine Fogging Oil is ideal for protecting internal engine components during long periods of inactivity. These steps ensure that whether the car is driven daily or stored seasonally, it remains protected from the elements and mechanical wear.
About the 2008 Mercedes-Benz CLS550
The 2008 Mercedes-Benz CLS550 represents a unique chapter in automotive history, effectively pioneering the “four-door coupe” segment that has since become a staple of the luxury market. Based on the CL-Class sedan platform but reimagined with a flowing, sporty roofline, it combines the practicality of a four-door vehicle with the aggressive aesthetics typically reserved for two-door coupes. The CLS550 is powered by the M273 5.5-liter naturally aspirated V8 engine, which was renowned for its smooth power delivery and refined performance. This engine, known for its robust engineering, produces significant torque and horsepower, making the CLS550 a capable grand tourer that could comfortably blend luxury with spirited driving dynamics.
Designed with a focus on both style and substance, the CLS550 appealed to buyers who wanted a vehicle that turned heads without sacrificing the utility of a family car. Its interior was crafted with high-quality materials, emphasizing comfort and luxury, while the chassis tuning provided a balance of handling precision and ride comfort. The vehicle’s reputation is built on its ability to offer a “sporty sedan” experience with the head-turning looks of a coupe, making it a favorite among enthusiasts who appreciate German engineering and design. While the 2008 model year is part of the first generation of the CLS line, it established the foundation for a model line that would continue to innovate and evolve, securing a dedicated following of owners who value its unique blend of performance and elegance.
Conclusion
Protecting the 2008 Mercedes-Benz CLS550 involves more than just an oil change; it requires a comprehensive approach to lubrication. By selecting the right synthetic motor oil, high-efficiency filter, and compatible fluids for the transmission and cooling system, owners can ensure their vehicle performs at its best for years to come. AMSOIL’s European-specific formulas provide the necessary protection to handle the thermal and mechanical demands of this luxury performance sedan, ensuring that every journey remains smooth, reliable, and efficient.