The 2021 BMW M850i xDrive represents the pinnacle of grand touring performance, combining a potent twin-turbo V8 engine with all-wheel-drive sophistication. To maintain the precise engineering standards of this high-performance vehicle, using the correct lubricants is not merely a suggestion but a requirement. The 4.4-liter N63B44T3 engine operates under extreme thermal and mechanical stress, demanding a fluid solution that resists oxidation, prevents sludge, and maintains optimal viscosity from the coldest winter mornings to the hottest track sessions.
Recommended AMSOIL Products
For the 2021 BMW M850i xDrive, we have identified the following lubricants designed to meet the stringent specifications of BMW’s European engines and drivetrains. These products ensure maximum protection and longevity for your investment.
- AMSOIL 0W-30 MS 100% Synthetic European Motor Oil – A specialized formula for European vehicles that offers precise additive blends to protect turbochargers and variable valve timing systems.
- WIX Oil Filter – Features premium filtration media that exceeds OEM standards to capture harmful contaminants and ensure clean oil flow.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A ready-to-use, phosphate- and silicate-free formulation that protects all cooling system metals against corrosion.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that provides superior heat transfer and corrosion protection when mixed with distilled water.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Designed to withstand the rigors of the ZF 8-speed automatic, providing stability under heavy load and extreme temperatures.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Delivers exceptional responsiveness for anti-lock braking systems and maintains viscosity stability across a wide temperature range.
Engine Oil Specifications and Maintenance
The heart of the M850i is the N63B44T3 engine code, a 4.4-liter twin-turbocharged V8. This engine requires a specific viscosity to ensure adequate protection for the turbochargers, piston cooling jets, and variable valve timing mechanisms. AMSOIL recommends the AMSOIL 0W-30 MS 100% Synthetic European Motor Oil for all operating temperatures. This oil is explicitly designed for the unique demands of gasoline, diesel, and hybrid European vehicles, featuring a precise blend of synthetic base oils and premium additives.
The capacity for the engine oil, including the filter replacement, is 11.1 quarts. When performing an oil change, it is critical to torque the oil drain plug to 30 ft-lbs and always replace the drain plug seal to prevent leaks. After refilling the system, the oil level should be checked and adjusted to the proper mark on the dipstick or electronic sensor. Using the correct oil filter, such as the WIX Oil Filter (Part No. 57189), ensures that the high flow rates of this powerful engine are not restricted and that particulate matter is effectively removed.
Transmission and Drivetrain Fluids
The M850i xDrive utilizes the ZF 8HP76Z 8-speed automatic transmission. This transmission is complex and sensitive to fluid degradation. Standard mineral-based fluids can quickly break down under the high torque loads and shifting speeds of the M850i. For this application, AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is the recommended choice. It is engineered to remain fluid in sub-zero temperatures while providing reserve protection during heavy use, such as spirited driving or towing.
The total fill capacity for the 8-speed automatic transmission is 9.8 quarts. While top-off procedures may require less, a complete fluid change ensures the removal of sludge and metal particles accumulated over time. This fluid protects against wear and temperature-related issues, allowing the transmission to shift smoothly and efficiently. For the xDrive all-wheel-drive system, while specific torque converter fluid is not listed in the summary, the use of high-quality AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid extends the life of the transfer case and differential components. Note that while front differential lubricant capacity is listed for other applications as 1.3 pints, the M850i relies on the specific transmission fluid for its automated transfer case operations.
Cooling System and Brake Fluid
Maintaining optimal operating temperatures is vital for the longevity of the twin-turbo engine. The cooling system capacity varies slightly depending on the specific antifreeze configuration (e.g., 9.2 quarts with OSA33T9, 3.4 quarts for LTCC3, or 10.6 quarts with SA33T1). To protect the cooling system, AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is recommended. This unique poly-organic acid (OAT) formulation is free of phosphates, nitrates, nitrites, silicates, borates, and amines, making it compatible with all cooling system metals, gaskets, and hoses.
For the braking system, the BMW M850i xDrive requires a high-performance fluid. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is designed to provide excellent ABS and traction-control responsiveness. Unlike conventional fluids, the synthetic formulation provides a stable viscosity over a wide temperature range, preventing brake fade during aggressive driving and ensuring consistent pedal feel. This fluid meets the BMW specifications for DOT 4 low viscosity, ensuring compatibility with the vehicle’s sensitive electronic brake systems.
Additional Maintenance and Performance Additives
Beyond standard lubricants, maintaining the 2021 BMW M850i xDrive benefits from the use of specialized additives and cleaners. AMSOIL P.i.® Performance Improver Gasoline Additive is highly recommended for GDI (Gasoline Direct Injection) engines. It helps restore up to 14% of horsepower by cleaning fuel injectors to 100% flow rate, effectively removing carbon deposits that can build up over time. This additive improves fuel economy and reduces the need for costly higher-octane fuel.
For vehicle owners who store their M850i during off-seasons or during periods of inactivity, AMSOIL Gasoline Stabilizer helps keep fuel fresh for up to 12 months, fighting ethanol corrosion and varnish buildup. Additionally, AMSOIL Engine Fogging Oil offers a highly-effective rust preventive for protecting internal engine components during storage. For general vehicle care, AMSOIL Heavy-Duty Metal Protector can be applied to undercarriage components to guard against the effects of salt and moisture, leaving a protective, wax-like coating that lasts for years.
Industry Testing and Driver Approval
The reliability of these AMSOIL products is backed by rigorous industry-standard testing. Whether you are extending the time between oil changes, driving in extreme temperatures, or pushing the vehicle through the added stress of a turbocharger, our motor oils provide the necessary protection. Over 6,000 customers have experienced the benefits of AMSOIL lubricants, confirming their effectiveness in real-world driving conditions. By choosing AMSOIL, you ensure that your BMW M850i xDrive receives the highest level of care available.
Vehicle Background
The 2021 BMW M850i xDrive sits at the top of the BMW 8 Series lineup, serving as a grand tourer that balances everyday usability with supercar-level performance. Based on the CLAR platform, which also underpins the 7 Series and i4, the M850i offers a sophisticated blend of comfort and power. It is powered by the BMW N63B44T3, a 4.4-liter twin-turbocharged V8 engine that delivers an impressive output of 523 horsepower and 553 lb-ft of torque. This powertrain is mated to a ZF 8-speed automatic transmission and the M xDrive all-wheel-drive system, which can be disengaged to operate in rear-wheel drive for a more dynamic driving experience.
Owners of the M850i xDrive typically appreciate its ability to cruise effortlessly at highway speeds while remaining ready to sprint from a standstill. The interior is crafted with premium materials, featuring leather upholstery, advanced technology, and a driver-focused cockpit. The car is known for its sharp handling, despite its substantial weight, thanks to electronic suspension control and rear-wheel steering. The xDrive system provides exceptional traction in all weather conditions, making it a versatile choice for owners who require a daily driver without sacrificing performance.
However, like any high-performance European vehicle with a twin-turbo V8, the M850i is not without its specific maintenance challenges. One common issue associated with the N63 engine family is oil consumption, where seals and piston rings can allow oil to burn off more rapidly than expected. Using a high-quality synthetic oil like AMSOIL 0W-30 MS 100% Synthetic European Motor Oil can help mitigate this by maintaining proper viscosity and reducing burn-off. Another potential concern is carbon buildup on the intake valves and fuel injectors, a common trait in GDI engines. The use of AMSOIL P.i. Performance Improver can help alleviate this by cleaning the fuel system and restoring injector flow rates.
Thermal stress is another factor, as the high-output engine can push cooling systems to their limits, especially during track days or spirited driving. The cooling system can suffer from premature corrosion or seal degradation if not protected by a compatible antifreeze. Additionally, the complex electronics and high-pressure fuel pumps in this vehicle require brake fluids and fuels that maintain consistency over time. By addressing these potential pain points with premium lubricants, owners can extend the life of critical components and maintain the vehicle’s peak performance characteristics.