The 2018 Audi A6 Quattro with the 3.0-liter turbocharged V6 engine (Engine Code CREH L) is a sophisticated luxury sedan that demands precision maintenance. The complex engineering of this powertrain, including the turbocharger, timing chain, and the Quattro all-wheel-drive system, places specific stresses on lubricants. Standard mineral oils cannot withstand the extreme heat and shear forces generated by this high-performance engine, particularly under hard driving conditions. Using the correct synthetic lubricants ensures optimal viscosity protection, reduces wear on critical components like the camshafts and bearings, and helps maintain the vehicle’s intended fuel economy and performance characteristics. This guide details the precise AMSOIL products and specifications required to keep your Audi in peak operating condition.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – Specifically formulated for European vehicles, this fluid offers premium protection and meets Audi specifications for extended drain intervals.
- AMSOIL 5W-40 MS 100% Synthetic European Motor Oil – A high-mileage option designed to reduce oil consumption and seal leaks while maintaining engine cleanliness.
- AMSOIL 0W-40 FS 100% Synthetic European Motor Oil – An ultra-low temperature viscosity grade that ensures rapid lubrication during cold starts while maintaining film strength at operating temperature.
- WIX Oil Filter (WL10345) – A premium filter with advanced media that captures microscopic contaminants, ensuring cleaner oil flow through the high-pressure lubrication system.
- WIX Oil Filter (WL10396) – An alternative premium filtration solution offering superior media performance and durability compared to original equipment filters.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A pre-mixed 50/50 formulation designed to protect the cooling system from corrosion and freezing without the need for water mixing.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated formula providing extended service life and enhanced safety for the cooling system.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Engineered to reduce friction for better fuel economy and withstand the high loads of the 8-speed automatic transmission.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective synthetic fluid that meets OEM requirements for smooth shifting and transmission protection.
- AMSOIL 75W-90 Long Life 100% Synthetic Gear Lube – Ideal for the front differential, offering extreme pressure protection and long-lasting lubrication for the Quattro system’s gears.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – A high-performance brake fluid that resists boil-over and maintains consistent pedal feel under repeated hard braking.
Engine Oil and Filtration for the 3.0L CREH L Engine
The heart of your 2018 Audi A6 Quattro is the 3.0-liter supercharged V6 engine, designated by the engine code CREH L. This powerplant is renowned for its smooth power delivery and responsiveness, but it requires fluid that can handle high temperatures and the demands of the turbo/supercharger system. The manufacturer specifies a particular oil viscosity and quality standard to ensure the longevity of the variable valve timing systems and the delicate oil pump gears.
For the oil change interval, the vehicle requires a capacity of 7.2 quarts when including the filter replacement. This volume accounts for the complete drainage of the oil pan, the oil cooler, and the filter housing. It is critical to refill the system to the exact level and check the dipstick after the engine has run to ensure proper circulation.
AMSOIL offers three primary choices to match your driving style and maintenance preferences. The AMSOIL 5W-40 FS 100% Synthetic European Motor Oil is the premier choice for drivers who want maximum protection and the ability to extend drain intervals beyond standard recommendations. It is formulated specifically for the synthetic base stocks required by European manufacturers, ensuring compatibility with the engine’s seals and emission systems.
Alternatively, the AMSOIL 5W-40 MS 100% Synthetic European Motor Oil is tailored for higher mileage vehicles or those showing signs of oil consumption. Its specialized additive package helps rejuvenate seals to reduce leaks and controls oil consumption without compromising film strength. For those driving in extreme cold climates or seeking the thinnest possible startup viscosity, the AMSOIL 0W-40 FS provides superior flow characteristics at low temperatures while maintaining a robust 40-weight film at operating temperature.
Filtration is equally vital for this engine. The oil filter WIX Oil Filter (WL10345-EA) or the WIX Oil Filter (WL10396-EA) are recommended replacements. These filters utilize advanced synthetic media that capture contaminants 10 times smaller than what standard paper filters can trap. Given the tight tolerances of the 3.0L engine’s bearings and the high pressure of its lubrication system, keeping the oil clean is paramount. Replacing the filter with a premium option ensures that abrasive particles do not circulate back into the engine, which can cause premature wear on the timing chain guides and camshaft lobes.
Transmission and Drivetrain Lubrication
The A6 Quattro utilizes a sophisticated all-wheel-drive system managed by a Haldex or similar coupling unit, paired with an 8-speed automatic transmission (code 0BK). The transmission is a critical component where proper fluid selection directly impacts shift quality and the lifespan of internal clutches.
For the automatic transmission, the capacity varies based on the fill method, with a total fill of 9.1 quarts required for a complete system flush, or approximately 3.8 quarts for an initial fill during a fluid change. The standard fluid often degrades over time, leading to delayed shifts or shuddering under load.
The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to withstand the rigors of heavy towing and elevated temperatures while maintaining low viscosity for optimal fuel efficiency. It provides a stable friction profile that ensures smooth gear changes and reduces the likelihood of transmission shudder, a common issue in modern automatic transmissions. For those seeking a more budget-friendly option that still meets all OEM specifications, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid offers excellent protection against wear and oxidation, ensuring the transmission remains responsive in all conditions.
The front differential also requires specific attention. The A6 Quattro front differential capacity is approximately 1.9 pints. The high stress placed on the gears during cornering and acceleration requires a lubricant with extreme pressure (EP) additives to prevent wear. The AMSOIL 75W-90 Long Life 100% Synthetic Gear Lube is engineered to provide high-load protection and improved cold-weather shifting. Its synthetic formulation resists thinning at high temperatures and provides better seal life, ensuring that the Quattro system continues to distribute power effectively without leaks or failure.
Cooling and Brake Systems
Maintaining the thermal balance of the 3.0L engine is essential, particularly given the heat generated by the supercharger. The cooling system holds a significant volume, with a capacity of 12.7 quarts. Over time, coolant breaks down and loses its ability to prevent corrosion, which can lead to costly damage to the aluminum water pump, heater core, and cylinder heads.
The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a unique poly-organic acid (OAT) formulation designed to protect all cooling system metals, gaskets, and hoses. This pre-mixed antifreeze is phosphate, nitrate, and silicate-free, making it safe for the delicate alloys used in Audi cooling systems. It offers protection up to 150,000 miles or 5 years. For those preferring a concentrated solution, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant provides a concentrated mix that can be tailored for specific freezing protection needs and offers extended service life in heavy-duty applications.
Brake fluid is another critical fluid that is often overlooked. The 2018 A6 utilizes DOT 4 brake fluid, which is hygroscopic and absorbs moisture from the atmosphere over time. This moisture lowers the boiling point of the fluid, potentially leading to a “spongy” pedal or brake fade during aggressive driving. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is engineered to provide a stable viscosity over a wide temperature range, ensuring excellent ABS and traction-control responsiveness. By flushing the system with synthetic brake fluid, you maintain a higher boiling point and protect the rubber seals within the ABS module and calipers from drying out.
Vehicle Background and Performance Profile
The 2018 Audi A6 Quattro represents the pinnacle of the C7 generation, a platform celebrated for its blend of executive luxury and dynamic driving capability. Produced by the German automaker Audi, the A6 is a mid-size luxury sedan that competes directly with the BMW 5 Series and the Mercedes-Benz E-Class. The specific model reviewed here features the 3.0-liter V6 supercharged engine (CREH L), which distinguishes itself from the four-cylinder options by offering a robust torque curve and a sophisticated power delivery that feels seamless across the rev range. This engine, often paired with an 8-speed Tiptronic automatic transmission and the renowned Quattro all-wheel-drive system, provides a driving experience that balances comfort with genuine sportiness.
Owners of the 2018 A6 Quattro often appreciate the vehicle’s quiet cabin, which serves as a sanctuary from road noise thanks to extensive sound insulation and acoustic glass. The interior is characterized by high-quality materials, including available leather trims, aluminum accents, and the signature Audi Virtual Cockpit digital instrument cluster. The Quattro system, which typically distributes power rearward to the front when needed, offers superior traction in adverse weather conditions, making the vehicle a reliable choice for year-round driving regardless of the climate.
While the 2018 A6 is a robust vehicle, like any high-performance European car, it is not without its potential maintenance challenges, especially as it ages. One common issue found in the C7 generation is carbon buildup on the intake valves, particularly in direct injection engines. Over time, this can lead to rough idling and reduced fuel economy. Using additives like AMSOIL P.i.® Performance Improver can help restore fuel injector flow and clear these deposits, improving engine efficiency.
Another frequent concern for high-mileage 3.0L engines is oil consumption. The piston rings may stretch or seals can harden over time, leading to oil burning or leaks. The AMSOIL 5W-40 MS formula is specifically designed to help control oil consumption in these scenarios, utilizing a unique additive package to condition seals and reduce burn-off. Additionally, the timing chain tensioners in these engines can wear, leading to rattling noises on startup. Maintaining clean oil with high-quality filters is critical to ensuring the hydraulic tensioners have sufficient flow to operate correctly.
A third issue involves the cooling system, specifically the electric water pump. These pumps can fail prematurely, leading to overheating. Using a high-quality antifreeze like AMSOIL Propylene Glycol Antifreeze can help extend the life of the water pump and prevent corrosion buildup that might foul the electric motor or impeller. Finally, the Quattro system’s differential can suffer from noise or stiffness due to fluid degradation. The synthetic gear lube ensures that the gears remain lubricated with a film that resists shear, preserving the longevity of the drivetrain components and ensuring that the vehicle continues to offer its signature handling balance.