The 2021 Mercedes-Benz CLS53 AMG is a high-performance luxury coupe built on the premium CLS platform, featuring the potent 3.0-liter inline-six engine equipped with an integrated starter generator and dual turbochargers. This engineering marvel demands precision lubrication to handle the intense thermal stress generated by its turbocharged powertrain and complex emission systems. Using a fluid that meets or exceeds the strict OEM specifications is critical for maintaining oil pressure, minimizing friction, and ensuring the longevity of internal components. For this specific vehicle, the engine requires a high-quality synthetic motor oil capable of flow at low temperatures while maintaining a stable film strength under heavy load.
Recommended AMSOIL Products
- AMSOIL 5W-30 LS 100% Synthetic European Motor Oil – Specifically formulated for European vehicles, offering precise additive blends that protect high-stress turbo engines and meet rigorous Mercedes-Benz standards.
- AMSOIL 5W-40 MS 100% Synthetic European Motor Oil – A robust option for drivers seeking slightly thicker protection, designed to handle the extreme heat and performance demands of AMG-tuned powertrains.
- AMSOIL 0W-20 LS 100% Synthetic European Motor Oil – The manufacturer-recommended viscosity that ensures optimal fuel economy and instant lubrication during cold starts for this specific 3.0L engine.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A phosphate-free, OAT formulation that exceeds OEM requirements to protect the aluminum cooling system from corrosion and overheating.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated, non-toxic option for those preferring propylene glycol chemistry, offering superior heat transfer properties for high-performance driving.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Designed to withstand heavy towing and elevated temperatures while providing smooth shifting and extended service intervals.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective synthetic alternative that delivers exceptional wear protection and fuel economy for modern automatic transmissions.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Provides excellent ABS responsiveness and a high boiling point to prevent vapor lock under the intense braking demands of an AMG performance vehicle.
The 3.0-liter 6-cylinder engine, identified by the code 256.930 2 Turbo, operates under significantly higher temperatures than standard naturally aspirated engines. The oil capacity for a complete change, including the filter, is approximately 9 quarts. It is crucial to check the oil level after refilling to ensure the dipstick or electronic sensor reads correctly, as overfilling or underfilling can compromise the engine’s operation. The recommended viscosities for this engine include 0W-20, 0W-30, and 0W-40 for all temperatures, with 5W-30 and 5W-40 being suitable for ambient temperatures above -25°C. Selecting the correct viscosity grade is essential for balancing the engine’s tight tolerances and protecting the turbocharger bearings.
Cooling System and Thermal Management
Effective thermal management is vital for the CLS53 AMG, particularly given the heat generated by the twin-turbo setup. The cooling system requires a high-performance AMSOIL Passenger Car & Light Truck Antifreeze & Coolant to prevent corrosion in the aluminum blocks and radiators. The system capacity involves both the main AMSOIL Propylene Glycol Antifreeze and Engine Coolant circuit and the heater circuit. For the main engine cooling system, the capacity is 14.8 quarts using a 50/50 pre-mix formulation. Alternatively, for a system requiring propylene glycol, a concentration of 4.2 quarts may be specified. AMSOIL’s antifreeze options utilize unique poly-organic acid technology (OAT) that is free from phosphates, nitrates, nitrites, silicates, borates, and amines. This formulation protects all cooling system metals, gaskets, and hoses, providing protection for up to 150,000 miles or 5 years.
For owners who prefer the safety of propylene glycol over traditional ethylene glycol, the concentrated AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers a versatile solution. This fluid requires mixing with distilled or high-quality water and is capable of lasting up to 150,000 miles or 5 years in passenger cars. It greatly surpasses standards for metallic corrosion and erosion, making it an excellent choice for preserving the integrity of the cooling system components in high-mileage vehicles.
Transmission and Differential Lubrication
The automatic transmission in the 2021 CLS53 AMG requires a fluid that can handle rapid shifts and high torque loads. While no specific filter recommendations are available for the transmission service, the fluid selection is critical. AMSOIL offers two primary choices for automatic transmission fluid. The Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed for the rigors of heavy towing and elevated temperatures, remaining fluid in sub-zero conditions to ensure reliable performance. The OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid provides excellent wear protection and is a highly regarded option for maintaining transmission health and fuel economy.
The differential and transfer case lubrication is also a key consideration for this all-wheel-drive capable model. For the transfer case, the capacity is approximately 1.5 pints, and the torque specifications are 18 ft-lbs for the drain plug and 10 ft-lbs for the fill plug. The front differential capacity is roughly 1.3 pints. Ensuring these gears are lubricated with a high-quality synthetic lubricant helps reduce noise and wear, maintaining the smooth power distribution between the front and rear axles. Proper lubrication here prevents the whine and vibration that can occur when gear oils break down under extreme stress.
AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid and Fluid Maintenance
Performance braking systems are a hallmark of the CLS53 AMG, and standard brake fluids can boil under hard driving conditions. The vehicle recommends DOT 4 Plus brake fluid. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is an ideal replacement that exceeds the original manufacturer’s requirements. This synthetic fluid provides a stable viscosity over a wide temperature range and ensures excellent responsiveness for the ABS and traction-control systems. By maintaining a high boiling point, it prevents vapor lock, which can lead to a dangerous loss of braking power, ensuring the vehicle remains safe and controllable even during spirited driving sessions.
Additional Care and Protection
Beyond the essential engine and chassis fluids, maintaining the overall health of the vehicle involves attention to fuel quality and cleanliness. AMSOIL P.i. Performance Improver Gasoline Additive is highly recommended for GDI (Gasoline Direct Injection) engines like the one in the CLS53. It helps restore fuel injectors to 100% flow rate and can restore up to 14% horsepower by removing carbon deposits that accumulate in the intake valves and combustion chambers. Additionally, the AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor works to lubricate the fuel system and upper cylinders, protecting internal components from wear.
For vehicle owners who store their CLS53 AMG seasonally or do not drive it daily, AMSOIL Gasoline Stabilizer helps keep fuel fresh for up to 12 months, protecting against varnish and gum buildup. For long-term storage, AMSOIL Engine Fogging Oil is an effective solution to prevent internal rust by coating cylinder walls and components. When it comes to keeping the vehicle’s exterior looking pristine, the Miracle Wash Waterless Wash and Wax Spray offers a convenient cleaning solution that traps dust and repels light dirt without the need for water. For engine bay maintenance, the Heavy-Duty Degreaser and Engine Degreaser can quickly remove tough grime and oil, allowing for a thorough inspection of the engine compartment.
About the Vehicle
The 2021 Mercedes-Benz CLS53 AMG is the third generation of the CLS coupe, a model that blends the sleek, four-door coupé silhouette of the S-Class sedan with the performance DNA of the AMG brand. Introduced to redefine the luxury sport sedan segment, the CLS53 AMG sits between the standard CLS 43 and the high-output CLS 63 in the lineup, offering a balanced mix of everyday comfort and track-ready capability. The vehicle is powered by the M256 3.0-liter inline-six engine, which features a 48-volt electric turbocharger and an integrated starter generator (ISG). This advanced powertrain technology not only reduces turbo lag but also provides significant torque boost, delivering performance that rivals V8 engines while maintaining improved fuel efficiency.
This model is widely celebrated for its stunning design, characterized by a sloping roofline and aggressive aerodynamics that set it apart from the boxier S-Class and E-Class sedans. Owners typically appreciate the CLS53 AMG for its versatile driving character, which can range from a serene cruiser with its adaptive suspension and air springs to a sharp, responsive handler in Dynamic Select’s Sport Plus mode. The interior is spacious enough for four adults, featuring the luxurious MBUX infotainment system with a panoramic sunroof and high-end Nappa leather upholstery. It occupies a unique market position as a premium coupe-sedan, appealing to buyers who want the practicality of a sedan with the style and presence of a luxury sports car.
While the CLS53 AMG is a robust machine, owners often report specific maintenance needs that can be mitigated with high-quality lubricants. One common issue in M256 engines is carbon buildup on the intake valves, a known characteristic of GDI engines that can lead to rough idling and reduced performance over time. Regular use of fuel additives like AMSOIL P.i. can help minimize this buildup and keep the engine running smoothly. Another area of concern involves the cooling system; like many high-performance vehicles, the CLS is prone to cooling system stress, and using a high-quality, phosphate-free coolant can extend the life of the water pump and radiator. Some owners also note that the transmission can feel hesitant or jerky in certain conditions, which can be alleviated by flushing with a high-performance synthetic transmission fluid that offers better friction modulation and heat dissipation. Finally, the electrically activated turbocharger and complex suspension components benefit greatly from the superior thermal stability and film strength provided by synthetic fluids, helping to prevent premature wear on these expensive components.
In summary, the 2021 Mercedes-Benz CLS53 AMG is a vehicle that rewards attentive owners with a blend of style, luxury, and performance. By adhering to a strict maintenance schedule that includes the use of AMSOIL’s advanced synthetic lubricants, owners can ensure that their vehicle continues to perform at its peak. Whether it is the engine, transmission, or cooling system, the use of premium fluids is the key to unlocking the full potential of this engineering masterpiece and ensuring its reliability for years to come.