The 2008 Mercedes-Benz CLK350 is a sophisticated grand tourer powered by a robust 3.5-liter V6 engine designed for performance and durability. To maintain its driving dynamics and engine longevity, using the correct lubricants is essential. German-engineered vehicles often have specific requirements for oil viscosity and additive packages that differ from standard domestic or Asian imports. Using the proper AMSOIL products ensures the CLK350 receives protection against wear, temperature extremes, and engine sludge, keeping the vehicle running smoothly for the long haul.
Recommended AMSOIL Products
For the 2008 Mercedes Benz CLK350 with the 3.5L engine, we have selected the optimal AMSOIL lubricants and filters to meet the manufacturer’s specifications and provide enhanced protection.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A specialized European formula designed for the unique demands of this Mercedes engine, offering precise additive blends for gasoline and hybrid vehicles.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – Ideal for extreme cold weather starts or high-performance driving, providing rapid flow and exceptional wear protection.
- AMSOIL Oil Filter – Features 99% filtration efficiency at 20 microns and greater capacity for contaminants to extend engine life and reduce wear.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Engineered to withstand severe towing and elevated temperatures while maintaining fluidity in sub-zero conditions for the 722.9 transmission.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Provides stable viscosity over a wide temperature range and ensures excellent ABS responsiveness for superior stopping power.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Reduces friction and resists heat breakdown to ensure quiet operation and extend seal life in the steering system.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A pre-mixed poly-organic acid formulation that offers protection up to 150,000 miles or 5 years, safeguarding all cooling system metals.
- AMSOIL P.i.® Performance Improver Gasoline Additive – Helps restore horsepower and fuel economy by cleaning fuel injectors and preventing carbon buildup.
Proper lubrication goes beyond just the engine. The cooling system in the CLK350 requires a coolant that can handle the thermal loads of a luxury sports coupe without causing corrosion to the aluminum components. AMSOIL antifreeze and coolant products are free of phosphates, nitrites, and silicates, ensuring compatibility with the Mercedes cooling system and providing protection against freeze and boil-over. Furthermore, the automatic transmission in this model is a sensitive 7-speed unit that benefits significantly from the shear stability and friction modifiers found in synthetic transmission fluids. Using the correct gear lube and differential fluid, even in limited quantities for this vehicle, contributes to overall drivetrain smoothness.
Engine Oil and Capacity Specifications
The heart of the 2008 Mercedes-Benz CLK350 is the 3.5L V6 engine, identified by engine code 3498cc W. This naturally aspirated powerplant requires high-quality synthetic lubrication to maintain its efficiency and performance. The oil capacity for this engine is 8.5 quarts when including a filter replacement. It is important to note that on models equipped with an oil cooler, additional oil may be needed if the cooler is drained during the service.
When adding oil, it is critical to allow at least five minutes after refilling or turning the engine off before checking the oil level on the dipstick to ensure an accurate reading. The oil drain plug torque specification is 22 ft/lbs, ensuring a secure seal without damaging the threads. AMSOIL recommends two primary viscosities for this vehicle depending on climate and driving style. For general use, the 5W-40 FS 100% Synthetic European Motor Oil offers excellent protection. For colder environments or extreme performance, the 0W-40 FS 100% Synthetic European Motor Oil is an excellent alternative, providing superior flow at startup.
Filtration and Air Intake
Cleaning the air entering the engine is just as vital as filtering the oil. A clogged air filter forces the engine to work harder, reducing fuel economy and power output. For the CLK350, the MANN-FILTERS Air Filters (Product Code C369832-EA) provide premium media that improves upon original equipment manufacturer filters, ensuring the engine breathes efficiently. This helps maintain optimal combustion and power delivery.
For oil filtration, the AMSOIL Oil Filter (Product Code EA15K39-EA) is the top recommendation for owners seeking maximum engine protection. It provides filtering efficiency of 99 percent at 20 microns, which is significantly finer than many competing filters. This higher efficiency traps wear-causing contaminants that would otherwise circulate through the engine bearings and camshafts. The filter also offers greater capacity for contaminants, extending the service interval compared to standard paper filters.
If an alternative filter is preferred, the WIX Oil Filter (Product Code 57078-EA) and the MANN-FILTERS Oil Filter (Product Code HU7185X-EA) are also available options. These filters feature premium media that offer improvements over OEM-branded filters, ensuring that your vehicle receives the protection it needs regardless of which brand of filter you choose. All three options are compatible with the engine requirements for this Mercedes model.
Transmission and Sealing Fluids
The automatic transmission fluid plays a crucial role in the longevity of the 722.9 transmission found in the CLK350. Whether the vehicle has the reduced-friction code (A89) or the standard code (SL057), the capacity for a total fill is 9 quarts for the 7-speed unit. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid (Product Code ATLPK-EA) is designed to withstand the rigors of heavy towing, elevated temperatures, and challenging terrain. It remains fluid in sub-zero temperatures, providing a reserve of protection during heavy use. The AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid (Product Code OTLQT-EA) is another option that protects against wear and is formulated for OE applications.
The braking system in this vehicle also requires attention. The 2008 CLK350 is compatible with DOT 4 brake fluid standards, specifically those meeting MB Sheet 331.0. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent ABS and traction-control responsiveness. It maintains stable viscosity over a wide temperature range, ensuring consistent pedal feel in both hot and cold conditions. Additionally, the power steering system benefits from the AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid, which reduces friction and helps seals remain soft to prevent leaks, a common issue in older luxury vehicles.
Why Owners Like This Vehicle
The 2008 Mercedes-Benz CLK350 represents a peak era for the brand’s sports coupe lineage. Part of the C-Class derived CL platform, this vehicle was designed to bridge the gap between a practical luxury sedan and a high-performance convertible. The 3.5L M272 V6 engine was celebrated for its smooth power delivery and relative ease of maintenance compared to the supercharged or larger displacement engines found in other Mercedes models. Owners appreciate the balance it strikes; it offers the prestige and build quality associated with German engineering without the overwhelming complexity sometimes found in higher-tier models.
Driving the CLK350 provides a refined experience characterized by a quiet cabin, precise steering, and a suspension that absorbs road imperfections while remaining composed during cornering. The interior is a hallmark of late-2000s luxury, featuring high-quality materials, ergonomic controls, and a driver-focused cockpit. The vehicle’s appeal extends to its versatility; the availability of a targa top and a folding hardtop variant allowed owners to enjoy open-air motoring in good weather while maintaining a coupe’s security and style. Its reputation for reliability, particularly when maintained with high-quality synthetic fluids, makes it a popular choice for enthusiasts who value a blend of performance and everyday usability. While it may not have the raw power of the SL-Class, the CLK350 delivers enough acceleration to satisfy spirited driving needs while remaining comfortable for daily commuting.
Additional Maintenance and Storage
For owners looking to extend the life of their CLK350 or prepare it for seasonal storage, AMSOIL offers a range of specialized additives. The AMSOIL P.i. Performance Improver is a powerful gasoline additive that can help restore up to 14% horsepower and clean GDI fuel injectors. For winter storage, the AMSOIL Gasoline Stabilizer can keep fuel fresh for up to 12 months, preventing varnish and gum buildup that can clog fuel lines. The AMSOIL Engine Fogging Oil is another essential product for long-term storage, providing a protective coating on internal engine components to prevent rust and corrosion during periods of inactivity.
Exterior maintenance is equally important for preserving the vehicle’s aesthetics. The AMSOIL High-Foam Car Shampoo breaks down road grime without stripping wax, while the AMSOIL Exterior Ceramic Spray provides a durable layer of protection against UV rays and water spots. Interior cleaners and detailers help maintain the luxury feel of the cabin, with options for both light lemon and scent-free cleaning to trap and eliminate odors. By utilizing the full range of AMSOIL products, from engine oil to car care chemicals, CLK350 owners can ensure their vehicle remains in top condition for years to come.
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