The 2007 Mercedes-Benz CLK350 is a sophisticated Grand Tourer built on the W209 chassis platform, powered by the reliable 3.5-liter M272 V6 engine. While this vehicle offers a blend of luxury and performance, its longevity depends heavily on maintaining the precise lubrication specifications required by German engineering. Using the correct oils and fluids ensures that the 3.5L engine, which requires 8.5 quarts of capacity, runs smoothly under extreme temperatures and heavy loads. Neglecting specific fluid requirements can lead to costly repairs, particularly in the transmission and cooling systems which are sensitive to fluid degradation.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A formula specifically designed for the unique demands of European gasoline and diesel engines, providing superior protection against high temperatures and wear.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An excellent option for all-weather protection, offering precise viscosity control and enhanced durability for the CLK350’s 3.5L engine.
- AMSOIL Oil Filter – Features a 99% filtration efficiency at 20 microns to trap wear-causing contaminants, extending engine life and maintaining oil flow.
- WIX Oil Filter – Offers premium media improvements over original equipment manufacturer-branded filters.
- MANN-FILTERS Oil Filter – Provides premium media improvements over original equipment manufacturer-branded filters.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Provides reserve protection during heavy use, towing, and elevated temperatures for the 7-speed 722.9 transmission.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective alternative that meets strict OEM specifications while protecting against wear and sludge.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A phosphate-free, OAT formulation that protects all cooling system metals and hoses up to 150,000 miles.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that surpasses corrosion standards and offers protection up to 150,000 miles or 5 years.
- 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.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Helps seals remain soft to prevent leaks while resisting heat for extended fluid life and quiet operation.
Why Proper Lubrication Matters for Your CLK350
The 2007 Mercedes-Benz CLK350 relies on a complex network of fluids to function as intended. The engine bay houses a 3.5-liter V6 that is engineered for high output, making the choice of motor oil critical. This engine calls for specific viscosity grades, such as 0W-30, 0W-40, 5W-30, or 5W-40 depending on the operating temperature, with a total capacity of 8.5 quarts when changing the filter. Using a conventional mineral oil can lead to increased wear, sludge buildup, and reduced fuel economy, whereas a high-quality synthetic European formula maintains fluidity in extreme heat and cold. For complete engine protection, pairing the AMSOIL 5W-40 FS 100% Synthetic European Motor Oil with the AMSOIL Oil Filter ensures optimal performance.
Equally important is the cooling system. With a capacity of approximately 7.4 quarts, the AMSOIL Passenger Car & Light Truck Antifreeze & Coolant must be compatible with the aluminum components and gaskets within the engine. AMSOIL’s phosphate-free antifreeze formulations provide protection against corrosion and erosion, ensuring the cooling system operates efficiently even under the thermal stress of highway driving or stop-and-go traffic. The correct AMSOIL Propylene Glycol Antifreeze and Engine Coolant mix also prevents freezing in winter and overheating during summer, which is vital for the longevity of the engine block and cylinder head.
Transmission and Differential Protection
The automatic transmission in the CLK350, specifically the 7-speed 722.9 unit, is a precision component that requires fluid meeting strict Mercedes-Benz specifications like SL057 or SL058. Depending on the presence of the reduced-friction code A89, the fluid must deliver specific friction characteristics to ensure smooth shifting and prevent slippage. The total fill capacity for a complete transmission service is 9 quarts. Regular fluid changes using a premium synthetic transmission fluid help manage the heat generated during transmission operation, protecting clutch packs and solenoids from premature failure. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to withstand heavy towing and high temperatures, while the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid provides reliable OEM-compliant protection.
While the rear differential does not require a full fluid change with every service, it is a component that benefits from regular lubrication. The rear differential capacity is 2.3 pints. Ensuring this area is properly lubricated prevents gear wear and whining noises that can occur as the vehicle ages. AMSOIL gear lubricants and synthetic grease offer superior resistance to thermal and oxidation degradation, which is essential for maintaining the integrity of the differential gears.
Brake and Steering System Safety
Safety features like the brake system must perform instantly in any weather condition. The CLK350 requires a AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid that meets DOT 4 standards, often specifically MB sheet 331.0. AMSOIL’s DOT 3 and DOT 4 100% Synthetic Brake Fluid provides a stable viscosity over a wide temperature range, which translates to better pedal feel and responsive braking. This is crucial for a vehicle that may be driven spiritedly or in emergency situations.
The power steering system also plays a role in the driving experience. The fluid used must reduce friction and protect seals to prevent leaks, which can be expensive to repair. AMSOIL’s synthetic multi-vehicle AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid helps keep seals soft and pliable, resisting the high temperatures generated by the power steering pump. This ensures quiet operation and prevents the stiffness that can develop as fluids break down.
Maintenance Filters and Cleaners
Filter quality is often overlooked but is essential for the internal health of the engine. The AMSOIL Oil Filter offers filtering efficiency of 99 percent at 20 microns, which is superior to many standard filters. It allows for lower restriction, keeping engine parts properly lubricated and reducing wear. Additionally, the MANN-FILTERS Air Filters ensures that the engine breathes clean air, which improves combustion and fuel efficiency. For fuel system maintenance, the AMSOIL P.i.® Performance Improver Gasoline Additive can help restore fuel injectors to 100% flow rate, improving horsepower and fuel economy while reducing the need for higher-octane fuel.
Vehicle Background and Ownership Experience
The 2007 Mercedes-Benz CLK350 is a significant model in the history of the CLK line, representing the second generation (W209) of this luxury coupe. Introduced in 2003, this generation featured a more aerodynamic design compared to its predecessor, with a sleek fastback roofline and a more integrated rear end. The CLK350 specifically was equipped with the 3.5-liter M272 V6 engine, a powerplant known for its smooth power delivery and refinement. This engine produced around 268 to 272 horsepower, offering a balanced driving character that was comfortable for daily commuting yet responsive enough for spirited driving on winding roads. The vehicle was marketed as a grand tourer, positioned between the C-Class and the higher-performance SLK or S-Class models, appealing to drivers who wanted style and performance without the aggressive handling dynamics of a sportscar.
Owners of the CLK350 generally appreciate its blend of luxury, comfort, and practicality. The interior was designed with high-quality materials, including leather upholstery and wood trim, creating a sophisticated environment. The ride quality is often described as plush, effectively absorbing road imperfections while maintaining a sense of stability. The V6 engine provides a smooth and quiet power delivery, which complements the vehicle’s grand touring intent. Many owners also value the ample trunk space compared to smaller sports cars, making it a viable choice for occasional long trips or weekend getaways.
However, like many high-mileage German vehicles, the CLK350 can encounter specific issues as it ages. One common problem is carbon buildup on the intake valves, which can lead to rough idling and reduced fuel efficiency. This is particularly prevalent in vehicles with the M272 engine as carbon accumulates on the valves due to the Positive Crankcase Ventilation (PCV) system. Regular use of a high-quality fuel additive like AMSOIL P.i.® Performance Improver Gasoline Additive can help mitigate this issue by cleaning the fuel injectors and preventing carbon buildup.
Another frequent concern for this model is oil consumption, which can be traced to the design of the piston rings and the PCV valve system. Over time, oil can seep into the combustion chamber, leading to increased oil usage between changes and potential fouling of spark plugs. Using a high-performance synthetic oil with advanced anti-wear additives can help seal these components and reduce consumption. Furthermore, the V6 engine is known to be sensitive to oil quality, and degraded oil can exacerbate issues with the variable valve timing system, which relies on consistent oil flow and pressure.
Leaking seals and gaskets are also a common occurrence in older CLK models. As the vehicle accumulates miles, rubber seals in the engine and transmission can harden and shrink, leading to leaks. AMSOIL synthetic oils and AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid are formulated to condition seals, helping them remain soft and pliable to prevent leaks. Additionally, the cooling system can be prone to leaks due to aging plastic components in the water pump and thermostat housing. Ensuring the cooling system is flushed with a high-quality AMSOIL Passenger Car & Light Truck Antifreeze & Coolant that is compatible with the specific metal and plastic components in the system is essential to prevent leaks and overheating. By addressing these common maintenance needs with the correct fluids and filters, owners can extend the life of their CLK350 and enjoy the driving experience it was designed to provide.