The 2008 Mercedes-Benz SL550 is a high-performance grand tourer powered by the robust 5.5L V8 engine (Engine Code 273.965 8). Maintaining this luxury sports car requires precise fluid specifications to ensure the longevity of its complex mechanical systems. From the sensitive high-compression engine to the sophisticated seven-speed automatic transmission, using the correct lubricants is essential for preventing wear, managing heat, and maintaining the vehicle’s renowned driving dynamics.
Owners of this SL-Class model benefit from a wide array of AMSOIL synthetic lubricants designed to meet or exceed the original equipment manufacturer’s stringent standards. Whether you are driving through extreme summer heat, navigating freezing winter conditions, or simply extending the interval between maintenance, premium synthetic fluids provide superior protection compared to conventional oils.
Recommended AMSOIL Products
Proper fluid selection begins with the engine oil. For the 2008 SL550, AMSOIL offers two distinct synthetic European motor oil formulations tailored for the 5.5L V8. Both oils provide exceptional thermal stability and wear protection, making them ideal for this powerful engine. The 5W-40 viscosity is optimized for a wide temperature range, while the 0W-40 option offers enhanced cold-start protection.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – Engineered specifically for the unique demands of gasoline, diesel, and hybrid European vehicles, featuring a precise blend of synthetic base oils and premium additives.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – Another premier European formula designed to handle the high stress and heat of luxury sports cars while maintaining fluidity in sub-zero temperatures.
- AMSOIL Oil Filter – Provides superior filtration efficiency of 99 percent at 20 microns, allowing lower restriction to keep engine parts lubricated and offering greater capacity for contaminants to reduce wear.
- WIX Oil Filter – A high-quality alternative featuring premium media that offers improvements over standard original equipment manufacturer (OEM) branded filters.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A unique poly-organic acid (OAT) formulation that protects all cooling system metals, gaskets, and hoses for up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that greatly surpasses standards for metallic corrosion and erosion, requiring mixing with distilled water for optimal performance.
- 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 7-speed transmission.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective fuel-efficient option that protects the transmission against wear and temperature-related issues.
Engine Oil Specifications and Capacities
The 5.5L V8 engine in the 2008 Mercedes-Benz SL550 requires a substantial amount of lubricant to ensure full coverage of its internal components. The manufacturer specifies a total capacity of 9.0 quarts for a complete fluid change, including the oil filter replacement. It is critical to adhere to this capacity; however, proper procedure dictates that after refilling the system, the oil level should always be checked to ensure accuracy.
AMSOIL offers two primary viscosity grades for this vehicle. The AMSOIL 5W-40 FS 100% Synthetic European Motor Oil is suitable for a broad range of operating temperatures and is designed with a European formula that features a precise blend of synthetic base oils and premium additives. This specific formulation is intended for the unique demands of gasoline, diesel, and hybrid European vehicles.
For drivers who frequently operate in extremely cold climates or prefer enhanced cold-start flow, the 0W-40 FS 100% Synthetic European Motor Oil is an excellent choice. This fluid allows for rapid oil circulation upon startup, reducing the risk of wear during the critical first moments of engine operation. Both oils are 100% synthetic, providing superior resistance to oxidation and thermal breakdown compared to conventional petroleum-based oils.
When performing an oil change, the filter is just as critical as the oil itself. The AMSOIL Oil Filter is designed to complement the synthetic motor oil by capturing wear-causing contaminants. It offers extended service life and helps maintain clean oil by filtering at a 99-percent efficiency rate at 20 microns. This high level of filtration ensures that abrasive particles do not circulate back into the engine block. An alternative, the WIX Oil Filter, is also available and offers premium media that improves upon the filtration capabilities of standard OEM filters. Both filters are essential for maintaining the high-revving performance of the SL550’s engine.
Transmission and Cooling System Fluids
The transmission system in the 2008 SL550 is a 7-speed automatic (722.9) that requires specific fluid characteristics to function correctly. For models without the reduced-friction code A89 on the data card, AMSOIL recommends two distinct options for automatic transmission fluid. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is engineered to withstand the rigors of heavy towing, elevated temperatures, and challenging terrain. It remains fluid even in sub-zero temperatures and provides reserve protection during heavy use or abuse, making it ideal for spirited driving.
The AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid offers a robust alternative that protects against wear and temperature-related problems without compromising fuel efficiency. The total fill capacity for the 7-speed transmission is 9.5 quarts. Using the correct synthetic fluid is vital for preventing sludge formation, wear, and costly transmission failures, ensuring the smooth power delivery that the SL550 is known for.
The cooling system plays a crucial role in maintaining the thermal balance of the engine and transmission. The vehicle’s cooling system requires 12.3 quarts of coolant. AMSOIL provides two excellent choices for this application. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a pre-mixed, ethylene glycol formulation that is phosphate, nitrate, nitrite, silicate, borate, and amine-free. It protects cooling system metals, gaskets, and hoses for up to 150,000 miles or 5 years. For those preferring a concentrated option, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers protection up to 150,000 miles (240,000 km) in passenger cars and light trucks. This concentrated formula greatly surpasses standards for metallic corrosion and erosion and must be mixed with distilled or high-quality water before use.
Performance Additives and Vehicle Care
To further enhance the performance and efficiency of the 2008 Mercedes-Benz SL550, AMSOIL offers specialized fuel additives. The AMSOIL P.i.® Performance Improver Gasoline Additive is designed to restore up to 14% horsepower and brings GDI (Gasoline Direct Injection) fuel injectors back to 100% flow rate after a single tank of treated fuel. It improves fuel economy and helps prevent carbon buildup, which is particularly beneficial for maintaining the efficiency of high-performance engines.
For seasonal storage, owners can utilize the AMSOIL Gasoline Stabilizer to keep fuel fresh for up to 12 months, protecting against varnish, gum buildup, and ethanol corrosion. Additionally, the AMSOIL Engine Fogging Oil is a highly effective rust preventive that can be used to protect internal engine components during long periods of inactivity, ensuring the car starts smoothly after being parked.
About the Vehicle
The 2008 Mercedes-Benz SL550 represents the pinnacle of German engineering within the R230 generation of the SL-Class roadster. Powered by the legendary M273 5.5-liter V8 engine, this grand tourer delivers a harmonious blend of effortless power and refined luxury. The engine, producing significant horsepower, is known for its smooth power delivery and responsive acceleration, making it a favorite among enthusiasts who appreciate both speed and comfort.
Built on the R230 platform, the SL550 features a lightweight aluminum body construction that contributes to its agile handling despite its substantial size. The vehicle is equipped with the 7-speed automatic transmission (722.9), which was an advancement over previous models, offering quicker shifts and improved fuel efficiency. This combination of a potent V8 engine and a sophisticated automatic gearbox allows the SL550 to serve as both a high-performance sports car and a comfortable daily driver.
Inside, the cabin offers a sophisticated environment with high-quality materials, adjustable sport seats, and advanced electronics typical of Mercedes-Benz luxury vehicles. The SL550 is often chosen by drivers who value exclusivity and the driving experience of a classic two-seat roadster but with modern reliability and technology. Its ability to handle long highway cruises with ease, coupled with the capability for spirited weekend driving, makes it a versatile choice for those who demand the best from their automobiles. Maintaining this vehicle with premium lubricants ensures that it continues to perform with the precision and reliability that the brand is famous for, keeping the suspension, engine, and transmission in top condition for years of ownership.
“`