The 2018 Mercedes-Benz GLS450 is a sophisticated full-size luxury SUV built on a robust platform that demands high-performance fluids to maintain its smooth ride and powerful acceleration. Under the hood, the vehicle utilizes a twin-turbocharged 3.0-liter inline-six engine, identified by the engine code 276.82 4, which operates at elevated temperatures and pressures. Selecting the correct lubricants is not merely a maintenance task; it is a critical component of preserving the integrity of this precision-engineered powertrain. Using synthetic oils formulated for European specifications ensures optimal flow during cold starts and stable film strength during the high-stress conditions of turbocharging and towing.
Recommended AMSOIL Products
For the 2018 Mercedes-Benz GLS450, AMSOIL offers specialized European formula oils designed to meet the stringent requirements of the MB 229.51 specification. These synthetic motor oils provide superior protection against sludge and varnish buildup, which is essential for the longevity of the engine’s variable valve timing and turbocharger systems.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – An excellent choice for temperatures above -25°C, this oil features a precise blend of synthetic base oils tailored for gasoline, diesel, and hybrid European vehicles, offering extended drain intervals and superior thermal stability.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – Ideal for use in all temperatures, this viscosity grade ensures rapid oil circulation during cold starts while maintaining a robust lubricating film at operating temperatures, protecting the turbocharger bearings and engine internals.
- WIX Oil Filter – Compatible with this vehicle, this premium filter utilizes high-grade media to capture microscopic wear particles, ensuring that the engine oil remains clean and the lubrication system flows freely.
The maintenance schedule for the GLS450 is strict, particularly regarding the oil capacity and filter changes. The engine requires 7.4 quarts of fluid when performing a complete change that includes the oil filter. When refilling, it is crucial to verify the oil level after the initial refill, as the dipstick provides the most accurate reading of the fluid status. The oil drain plug torque should be set to 22 ft/lbs for the metal plug to prevent leaks or stripped threads.
Beyond the engine, the cooling system requires attention to prevent overheating, a common issue in turbocharged engines that have seen high mileage. The GLS450 utilizes a specific volume of AMSOIL Passenger Car & Light Truck Antifreeze & Coolant depending on whether the system is being topped off or completely flushed. For a partial fill, the capacity is 1.9 quarts, while a full system refill requires 11.1 quarts. To ensure maximum corrosion protection for the aluminum components and rubber hoses within the cooling system, this product is a suitable option. This product is a phosphate-, nitrate-, nitrite-, silicate-, borate-, and amine-free formula that extends protection up to 150,000 miles or five years. For those preferring a concentrated solution that allows for custom mix ratios, AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers a robust alternative that greatly surpasses standards for metallic corrosion and erosion.
Brake system integrity is equally vital for a vehicle of this size. The 2018 GLS450 requires a high-quality fluid that meets DOT 4 standards, specifically those approved on MB Sheet 331.0. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent responsiveness for the vehicle’s ABS and traction control systems. Its stable viscosity over a wide temperature range ensures consistent pedal feel and prevents the moisture absorption that leads to rust and brake failure. The front differential and transfer case, while having smaller capacities, also benefit from regular lubrication to maintain the vehicle’s four-wheel-drive capabilities and towing capacity.
Vehicle Background
The 2018 Mercedes-Benz GLS450 represents the pinnacle of Mercedes-Benz’s luxury SUV lineup, often referred to as a four-door “S-Class” for the road. Based on the X166 platform, this third-generation GLS is a full-size luxury SUV that prioritizes both on-road refinement and off-road capability. The 3.0L 6-cylinder twin-turbo V-6 engine, part of the M276 family, delivers a seamless power curve that allows the massive SUV to accelerate with surprising agility. It is a flagship vehicle designed to transport passengers in absolute comfort while offering the versatility required for hauling large loads or navigating challenging terrain.
Owners of the 2018 GLS450 generally appreciate the blend of modern technology and traditional luxury. The interior features high-quality materials, advanced driver-assistance systems, and a spacious cabin that seats up to seven passengers. The vehicle is equipped with an air suspension system that adapts to driving conditions, providing a smooth ride even on uneven surfaces. Its market position is firmly as a premium alternative to other full-size luxury rivals, offering a sophisticated blend of power and elegance that appeals to families and executives alike.
Despite its engineering excellence, the GLS450 can encounter specific issues over time, particularly as the vehicle ages beyond the standard warranty period. One common area of concern is carbon buildup on the intake valves, a typical characteristic of Direct Injection engines. This accumulation can restrict airflow and reduce performance. Using a gasoline additive like AMSOIL P.i.® AMSOIL P.i.® Performance Improver Gasoline Additive can help restore fuel injector flow and mitigate these deposits, ensuring the turbocharged engine continues to breathe efficiently. Another potential issue involves the cooling system, where overheating can occur due to thermostat failures or sensor malfunctions. This is particularly critical for engines with aluminum blocks and heads that are sensitive to thermal stress. Maintaining a superior AMSOIL Propylene Glycol Antifreeze and Engine Coolant with extended protection capabilities helps stabilize operating temperatures and prevents costly warping or cracking of engine components.
Additionally, AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid moisture absorption is a silent killer of modern braking systems. As moisture enters the brake lines, it lowers the boiling point, leading to pedal fade during hard braking. Regular replacement with a high-quality synthetic brake fluid helps mitigate this risk and ensures the ABS system remains responsive. Finally, the vehicle’s air suspension system, while a feature of luxury, can be prone to leaks in the air struts as mileage increases. While oil changes do not directly fix air leaks, keeping the vehicle well-maintained with quality lubricants reduces the overall stress on the chassis and suspension components, potentially prolonging the life of these expensive systems. By addressing these specific vulnerabilities with high-grade fluids, GLS450 owners can enjoy years of reliable and luxurious driving.
Maintenance of this vehicle should not be treated as a generic procedure. The specific requirements of the European engine code 276.82 4 dictate the need for fluids that meet exacting standards. Using the recommended AMSOIL products ensures that the GLS450 continues to perform as intended, providing the driver with the confidence that comes from knowing their vehicle is protected with industry-leading technology.