The 2009 Mercedes-Benz G55 AMG with its 5.5-liter V8 engine (Engine Code 113.993 Q) represents a pinnacle of German engineering, combining off-road capability with high-performance street driving. However, this robust engine places specific demands on its lubrication system. Operating at high temperatures and RPMs requires synthetic lubricants that can withstand thermal stress, prevent sludge buildup, and ensure precise timing of the variable valve timing components found in the M113 engine family. Using the correct viscosity and fluid specifications is not just about meeting a checklist; it is about preserving the longevity of critical internal components and maintaining the vehicle’s legendary handling characteristics.
Recommended AMSOIL Products
For owners of this specific model, we have identified the premier AMSOIL products that match the factory specifications while offering superior synthetic protection.
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A precise European formula designed for the specific demands of gasoline, diesel, and hybrid vehicles, featuring a blend of synthetic base oils and premium additives to ensure stability under heat.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An excellent alternative viscosity for extreme temperature protection, maintaining optimal flow during cold starts while providing a robust film strength at high operating temperatures.
- AMSOIL Oil Filter – Delivers filtering efficiency of 99 percent at 20 microns, allowing for lower restriction to keep engine parts lubricated and providing greater capacity for contaminants to reduce engine wear over extended service intervals.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An OAT formulation engineered to exceed OEM requirements, offering protection up to 150,000 miles or 5 years and ensuring compatibility with all cooling system metals, gaskets, and hoses.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Formulated to withstand the rigors of heavy towing and elevated temperatures while remaining fluid in sub-zero conditions, providing reserve protection for the 722.6 transmission.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Delivers excellent ABS and traction-control responsiveness with stable viscosity across a wide temperature range to ensure reliable stopping power in demanding driving scenarios.
- WIX Oil Filter – Offers premium media that improves upon original equipment manufacturer filters, ensuring reliable flow and filtration.
- MANN-FILTERS Oil Filter – Provides advanced filtration capabilities compatible with the vehicle’s engine requirements.
Proper lubrication begins with the engine oil. The 2009 G55 AMG requires a high-quality synthetic blend that can handle the high output of the 5.5L V8. With a capacity of 9.0 quarts (including filter), this engine benefits significantly from the extended service life provided by AMSOIL’s European Formula oils. The 5W-40 FS option is ideal for most operating conditions, offering a precise balance of cold-flow properties and high-temperature stability. Alternatively, the 0W-40 FS provides enhanced cold-start protection while maintaining a thick protective film when the engine is under load. It is crucial to torque the oil drain plug to the correct specification of 22 ft/lbs to prevent leaks without stripping the threads.
Moving beyond the crankcase, the cooling system of this luxury SUV requires a coolant that prevents corrosion and boiling. The system holds 13.4 quarts of fluid. AMSOIL offers both a pre-mixed 50/50 ethylene glycol formulation and a concentrated propylene glycol option. The proprietary OAT (Organic Acid Technology) chemistry in these coolants provides superior protection against corrosion compared to traditional inorganic formulas, safeguarding the aluminum and steel components within the cooling loop for up to 5 years or 150,000 miles.
The automatic transmission in the G55 AMG is equally sensitive to fluid degradation. Designed for the 5-speed 722.6 transmission, it requires a fluid that can manage the torque and heat generated by the 500+ horsepower V8 engine. The Signature Series Fuel-Efficient Automatic Transmission Fluid is recommended for its ability to remain fluid in sub-zero temperatures while providing heavy-duty protection during high-temperature excursions. Alternatively, the AMSOIL OE Fuel-Efficient fluid offers wear protection for daily driving. The system requires a total fill of 9 quarts to ensure proper lubrication of the valve body and torque converter.
Essential Fluids for Complete Protection
Brake and power steering fluids are often overlooked but play a critical role in the safety and operation of the G55 AMG. The brake system requires a fluid that meets MB Sheet 331.0 specifications, such as DOT 4 plus. The AMSOIL DOT 3 and DOT 4 Synthetic Brake Fluid ensures consistent pedal feel and prevents moisture absorption, which can lead to boiling and corrosion within the ABS module. For power steering, the AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid helps reduce friction, keeps seals soft to prevent leaks, and offers strong anti-wear protection to maintain quiet operation.
For seasonal storage or long-term maintenance, AMSOIL offers a range of additives. The P.i.® Performance Improver can help restore up to 14% horsepower in fuel-injected engines by cleaning injectors and combustion chambers. Additionally, the Gasoline Stabilizer is ideal for vehicles that may sit idle, keeping fuel fresh for up to 12 months and protecting against varnish and gum buildup. The Engine Fogging Oil provides an essential layer of rust prevention for internal components during periods of inactivity, ensuring the engine is ready to run when needed. The AMSOIL Upper Cylinder Lubricant further lubricates the fuel system and upper cylinders for added protection.
About the Vehicle
The 2009 Mercedes-Benz G55 AMG is a unique iteration of the legendary G-Class, often referred to as “G-Wagen.” Unlike standard luxury SUVs, the G55 AMG retains the rugged, boxy, and utilitarian design lineage that traces back to the military vehicle origins of the platform. However, this specific model distinguishes itself by housing the high-output M113 5.5-liter V8 engine, which delivers substantial power and torque, making it one of the more performance-oriented variants of the G-Class available at the time.
Drivers and enthusiasts value this vehicle for its exceptional versatility. It is capable of serious off-road maneuvers thanks to its solid axles and three locking differentials, yet it possesses the refined ride quality and on-road dynamics expected of a Mercedes-Benz. The G55 AMG is a statement piece, offering a rare combination of brute force and luxury. Its reputation is built on durability and the ability to handle extreme conditions, whether navigating a rugged trail or cruising through a city center. The robust construction of the body-on-frame chassis allows it to withstand the wear and tear of demanding use, making it a favorite among collectors and off-road enthusiasts alike. While it commands a significant presence on the road, its mechanical simplicity compared to newer independent-suspension models appeals to those who prioritize mechanical robustness and traditional engineering values.