Maintaining the optimal performance of your 2016 Mercedes-Benz GL550 requires more than just following a rigid maintenance schedule; it demands the use of lubricants engineered specifically for the unique demands of European luxury engineering. This vehicle, powered by a 4.7-liter twin-turbocharged V8 engine (Engine Code 278.928.5), places significant stress on its internal components, particularly during high-speed driving, towing, or extended trips. The right fluid choice ensures that every moving part from the turbocharger bearings to the complex transmission gears receives the precise protection needed to prevent wear, reduce heat, and maintain peak efficiency.
Recommended AMSOIL Products
For owners seeking maximum protection and extended performance intervals, AMSOIL offers a comprehensive suite of synthetic lubricants designed to meet and exceed the stringent requirements of the GL550. The following products are the top recommendations for this specific vehicle.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – An ideal choice for normal operating conditions, this oil is formulated with a precise blend of synthetic base oils and premium additives specifically designed for the high-temperature demands of European turbocharged engines.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – Perfect for extreme temperature variations or severe service, this synthetic oil provides superior cold-start protection while maintaining a stable viscosity under high heat.
- WIX Oil Filter – Engineered to outperform original equipment manufacturer (OEM) standards, this filter uses premium media to trap contaminants, ensuring cleaner oil circulates through your engine for extended service intervals.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Provides robust protection for the 722.909 transmission, withstanding heavy towing, elevated temperatures, and challenging terrain while ensuring smooth shifts.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A high-performance alternative for owners who prefer a slightly different formulation, this fluid offers excellent protection against wear and extends transmission life.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Designed for vehicles requiring DOT 4 compliance, this fluid offers excellent ABS and traction-control responsiveness with a stable viscosity over a wide temperature range.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A convenient pre-mixed, 50/50 solution that protects cooling system metals, gaskets, and hoses for up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated, non-ethylene glycol option that offers extreme protection against corrosion and erosion, ideal for those who prefer mixing their own coolant blends.
Selecting the correct oil for your GL550 is the first step in preserving its engineering integrity. The 4.7L V8 engine is a sophisticated powerplant that relies on high-quality lubricants to manage the intense heat generated by its twin turbochargers. Standard mineral oils can break down under these conditions, leading to sludge buildup and increased wear. By utilizing the synthetic options listed above, you ensure that your engine remains clean, cool, and protected regardless of the driving conditions you encounter.
Engine Oil and Filtration Specifications
When performing an oil change on the 2016 Mercedes-Benz GL550, precision is key. The engine requires a total capacity of 9.0 quarts when the oil filter is replaced. This figure is critical; underfilling can lead to inadequate lubrication, while overfilling may cause foaming and pressure issues. The oil drain plug should be torqued to 22 ft/lbs if it is a standard M14 bolt, or 3 ft/lbs if it is a plastic component, ensuring a secure seal without risking damage to the threads. For the filter, the WIX Oil Filter (Part No. 57059) is the recommended choice, offering superior filtration efficiency compared to many stock options.
Viscosity selection depends on your operating environment. The AMSOIL 5W-40 FS is a versatile choice for general use, offering a robust protective film at high temperatures. For those living in regions with extreme cold or who engage in high-performance driving that generates significant heat, the AMSOIL 0W-40 FS provides a wider operating window, ensuring instant oil flow at startup and stability during heavy load conditions.
Transmission and Drivetrain Fluids
The transmission in the GL550 is a complex 7-speed automatic unit (722.909) that benefits greatly from synthetic fluid. The total fill capacity for this transmission is approximately 9.5 quarts. It is important to note that some vehicles may have a “Reduced Friction” option (Code A89) indicated on the datacard, which does not alter the capacity but requires specific fluid characteristics to function correctly. Both the AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid and AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid are formulated to withstand the rigors of this transmission, including the heat generated during city driving or when towing.
For the transfer case, the fluid requirements vary based on whether the vehicle is equipped with a single-speed or double-speed system. A single-speed transfer case requires 1.1 pints of lubricant, while a double-speed unit requires 3.2 pints. The same high-performance synthetic transmission fluid used in the gearbox can be effectively used here, providing excellent resistance to thermal degradation and ensuring smooth power transfer to all four wheels. The front differential, meanwhile, requires 1.7 pints of lubricant to keep the gears spinning smoothly and quietly.
Cooling System and Brake Fluid
Keeping the cooling system in top shape is vital for a twin-turbo engine, which operates at higher thermal loads than standard vehicles. The cooling system capacity is 12 quarts. AMSOIL offers two distinct solutions for this application. The Passenger Car & Light Truck Antifreeze & Coolant is a pre-mixed, ready-to-use formulation that protects against rust, corrosion, and freeze-up for up to 150,000 miles. For those who prefer a concentrated formula, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers even higher boiling points and superior heat transfer properties, making it an excellent choice for preventing boil-over during extreme summer driving or heavy towing.
Brake system safety should never be compromised. The GL550 utilizes DOT 4 standard brake fluid. Over time, brake fluid absorbs moisture from the air, which lowers its boiling point and can lead to brake fade under hard stopping. AMSOIL’s DOT 3 and DOT 4 100% Synthetic Brake Fluid is designed to resist this boiling point drop, ensuring consistent pedal feel and maximum stopping power even after repeated heavy use.
Additional Maintenance and Protection
Beyond the essential fluids, maintaining the cleanliness and performance of your GL550 involves a few additional steps. For fuel system health, AMSOIL P.i.® Performance Improver Gasoline Additive is highly recommended. This additive helps clean injectors, restore horsepower, and improve fuel economy, which is particularly beneficial for vehicles with Gasoline Direct Injection (GDI) systems. Additionally, if you plan to store the vehicle during off-seasons, AMSOIL Gasoline Stabilizer can keep fuel fresh for up to 12 months, preventing gum and varnish buildup that can clog injectors.
For those who enjoy the off-road capabilities of the GL550 or live in areas with heavy road salt, protective measures for the body and undercarriage are wise. Products like the AMSOIL Heavy-Duty Metal Protector can be sprayed onto hard-to-reach metal surfaces to provide a long-lasting barrier against rust and corrosion. Similarly, regular cleaning with products like the AMSOIL Power Foam® Carburetor and Induction-System Cleaner or AMSOIL Miracle Wash Waterless Wash and Wax Spray can keep the exterior free of grime and contaminants that might otherwise degrade the paint and clear coat.
Vehicle Background and Engineering Context
The 2016 Mercedes-Benz GL550 represents a pinnacle of luxury SUV engineering, combining the robustness of an off-road capable vehicle with the refinement of a high-end passenger sedan. This model is part of the GL-Class lineup, which sits between the larger G-Class and the smaller GLC-Class in Mercedes’ portfolio. Under the hood lies the M278 4.7-liter twin-turbocharged V8 engine, a powerhouse that delivers exceptional performance while incorporating cylinder deactivation technology to improve fuel efficiency when full power isn’t needed.
This generation of the GL550 was known for its commanding presence and advanced technology. It features the AIRMATIC air suspension system, which automatically adjusts ride height and damping for both comfort and handling, offering a smooth ride even on rough terrain. The interior is typically appointed with premium materials, offering a quiet and opulent cabin environment that contrasts with the vehicle’s rugged capabilities. Whether navigating city streets or embarking on a cross-country adventure, the GL550 is designed to do so with confidence and ease. The complexity of its systems, from the turbocharged engine to the sophisticated air suspension and 4MATIC all-wheel-drive system, makes the use of high-quality, specialized lubricants not just a recommendation, but a necessity for maintaining its longevity and performance characteristics.
By adhering to a strict maintenance schedule and utilizing the recommended AMSOIL synthetic lubricants, owners can ensure that their 2016 GL550 continues to perform like a new vehicle for years to come. The investment in these premium fluids pays dividends in reduced wear, cleaner engine operation, and a smoother driving experience.