The 2018 Infiniti Q50 equipped with the naturally aspirated 3.5L V6 (Engine Code VQ35HR) is a performance sedan known for its smooth power delivery and refined chassis dynamics. To maintain the reliability of the Q50’s engine and drivetrain, using the correct high-performance synthetic lubricants is essential. The VQ35HR engine benefits significantly from superior wear protection and thermal stability, which are hallmarks of AMSOIL synthetic formulations. This guide outlines the precise fluid capacities, recommended filters, and lubrication intervals to keep your Infiniti running at peak efficiency.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – Provides unmatched engine protection and extends service intervals up to 25,000 miles or one year.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – Delivers 20,000 miles of guaranteed protection with superior cleaning power to keep the engine running smoothly.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – A high-performance synthetic option that fights sludge and deposits, offering extended life and protection against wear.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Specifically formulated for engines with over 75,000 miles to reduce sludge and restore performance.
- AMSOIL Oil Filter (EA15K12-EA) – Offers 99% efficiency at 20 microns, allowing for lower restriction and extended service life to match synthetic oil.
- WIX Oil Filter (51358-EA) – A premium aftermarket alternative with improved media that outperforms original equipment manufacturer branded filters.
- WIX Air Filter (49225-EA) – Features premium media to ensure optimal airflow and filtration for the VQ35HR engine.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Designed to withstand heavy towing and elevated temperatures while ensuring smooth shifts.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Protects against wear and provides excellent cold-weather performance for the RE7R01H transmission.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Provides advanced protection for front GL-5 differentials with friction modifiers for limited-slip applications.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Offers superior protection against thermal runaway and rust for the rear differential requiring 75W-90.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A unique OAT formulation protecting all cooling system metals for up to 150,000 miles or 5 years.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures stable viscosity over a wide temperature range for excellent ABS and traction-control responsiveness.
Understanding the specific fluid requirements for the Q50’s VQ35HR engine helps prevent premature wear and ensures longevity. The engine oil capacity for a standard oil change, including the filter replacement, is 5.2 quarts. It is crucial to use the correct oil grade, which is 5W-30, to ensure proper lubrication across all operating temperatures. After refilling, always check the oil level to confirm the correct volume has been added. For those with vehicles exceeding 75,000 miles, the AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil provides enhanced seal conditioners and anti-wear additives to reduce oil consumption and sludge buildup.
Complete Fluid and Filter Guide
Maintaining the drivetrain of the 2018 Infiniti Q50 requires attention to the automatic transmission, differentials, and cooling system. The vehicle is equipped with a 7-speed RE7R01H automatic transmission that requires a specific fluid to handle the rigors of shifting and temperature fluctuations. A total fill for this transmission system is 7.4 quarts. AMSOIL offers synthetic transmission fluids designed to remain fluid in sub-zero temperatures and provide reserve protection during heavy use. Using a premium fluid like the Signature Series Fuel-Efficient Automatic Transmission Fluid can help maintain shift quality and protect against sludge formation over time.
The differential systems also demand precise lubrication. The front differential, which adheres to GL-5 specifications, has a capacity of 1.4 pints and requires an 80W-90 synthetic gear lube. AMSOIL SEVERE GEAR® 80W-90 is an excellent choice, offering protection against rust, corrosion, and thermal runaway. For the rear differential, which holds 2.2 pints, a 75W-90 synthetic gear lube is required. AMSOIL SEVERE GEAR® 75W-90 is specifically engineered to handle high loads and improve seal life, ensuring smooth operation and preventing premature wear in the rear axle assembly.
The cooling system is another critical component that benefits from high-quality coolant. Depending on the specific configuration (AWD or RWD), the pressurized tank capacities vary, ranging from 10.4 to 11.4 quarts. AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is an ethylene glycol 50/50 pre-mix formulation that protects all cooling system metals, gaskets, and hoses. For those who prefer a concentrated option, the Propylene Glycol Antifreeze and Engine Coolant offers even longer service intervals, up to 150,000 miles or 5 years. Both options are phosphate-, nitrate-, and silicate-free, ensuring compatibility with all coolant colors and preventing corrosion.
In addition to fluids, the air and oil filtration systems play a vital role in the vehicle’s performance. The WIX Air Filter (49225-EA) and the WIX Oil Filter (51358-EA) are excellent alternatives to OEM filters, featuring premium media that provides superior filtration efficiency. For the AMSOIL synthetic oil option, the EA15K12-EA Oil Filter is the recommended pairing, designed to match the extended drain intervals of synthetic oils with a capacity for small, wear-causing contaminants.
Brake and Maintenance Additives
Brake performance is paramount for safety, and the Q50 utilizes hydraulic brake fluid that meets DOT 3 specifications. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid offers superior stability over a wide temperature range, ensuring that the braking system responds reliably in all conditions. This synthetic fluid helps maintain consistent pedal feel and protects against moisture contamination, which can lead to corrosion in the brake lines and calipers.
For owners looking to maximize the efficiency of the 3.5L engine, AMSOIL P.i.® Performance Improver Gasoline Additive is a recommended addition. This additive helps restore up to 14% horsepower and clears carbon deposits from GDI fuel injectors, restoring them to 100% flow rate. By using this additive, owners can improve fuel economy and reduce the need for higher-octane fuels, all while helping prevent pre-ignition knock.
About the Vehicle
The 2018 Infiniti Q50 represents the continuation of a lineage that Infiniti introduced to the North American market in 2013, replacing the G37 and G35 models. This sedan was built on the Nissan D platform, a chassis design known for its rigidity and balanced weight distribution, which contributes significantly to the vehicle’s agile driving dynamics. The Q50 is widely recognized for offering a compelling mix of luxury, performance, and technology at a price point that undercuts many of its European rivals.
The 3.5-liter VQ35HR engine discussed in this guide is a naturally aspirated variant of Infiniti’s legendary VQ series. This engine is celebrated for its smoothness, high-revving capability, and reliability. While the Q50 also became famous for its later “Twin-Turbo” variants, the VQ35HR remains a favorite among enthusiasts who appreciate the linear power delivery and distinct exhaust note of a naturally aspirated V6. The engine produces approximately 328 horsepower, providing spirited acceleration without the complexity associated with forced induction systems.
Infiniti designed the Q50 to compete directly with the BMW 3 Series and Mercedes-Benz C-Class, yet it distinguished itself with features like Direct Adaptive Steering. This system allowed drivers to choose between a traditional steering feel and a more direct, “variable ratio” feel that changes based on steering angle. This innovation made the Q50 stand out in the luxury sedan segment, offering a more engaging driving experience.
While the Q50 is generally a reliable vehicle, owners of the 3.5L model should be aware of a few common maintenance considerations. One frequent issue involves the Engine Control Module (ECM) software, which can sometimes lead to rough idling or stalling; this is often resolved with a software update but can be mitigated by using high-quality synthetic oil that keeps the engine clean. Another area of attention is the oil pan gasket, which can occasionally develop leaks over time; the use of AMSOIL’s high-mileage formulation with enhanced seal conditioners can help prevent or slow down oil leaks by maintaining the flexibility of the seals. Additionally, the Variable Valve Event and Lift (VVEL) system, which controls the intake valves, can sometimes suffer from carbon buildup on the intake valves, particularly in stop-and-go driving conditions; regular use of a fuel injector cleaner like AMSOIL P.i. can help keep these systems clean and responsive. Finally, the battery and alternator connections can sometimes corrode, leading to electrical gremlins; using AMSOIL Heavy-Duty Metal Protector to shield metal surfaces from corrosion can be a proactive step for owners concerned about electrical issues.
Whether you are commuting daily or taking advantage of the Q50’s sport mode on a back road, using the correct lubricants ensures that the vehicle performs as Infiniti intended. By adhering to the recommended fluid specifications and utilizing high-performance synthetic products, owners can extend the life of their vehicle and enjoy a smoother, more reliable driving experience.