Ensuring your 2018 Genesis G90 receives the highest level of protection begins with selecting the correct lubricants and fluids. This luxury sedan, powered by the 5.0L V8 engine (Engine Code [H] H), demands specific synthetic lubricants to maintain its performance and longevity. Using the wrong viscosity or fluid type can compromise the engine’s ability to handle high temperatures and the transmission’s precision shifting. The following guide outlines the precise fluid capacities, specifications, and recommended AMSOIL products designed to meet or exceed the manufacturer’s requirements for this specific vehicle.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-20 100% Synthetic Motor Oil – Offers maximum protection with 75% more engine protection against horsepower loss and wear. Best for those extending oil change intervals up to 25,000 miles or 1 year.
- AMSOIL Extended-Life 5W-20 100% Synthetic Motor Oil – Provides 37% more cleaning power to keep the engine running smoother and offers 20,000 miles of guaranteed protection.
- AMSOIL OE 5W-20 100% Synthetic Motor Oil – A budget-friendly 100% synthetic option that fights sludge and deposits effectively.
- AMSOIL 5W-20 100% Synthetic High-Mileage Motor Oil – Formulated for vehicles with over 75,000 miles, featuring boosted detergents to reduce sludge by 67%.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol 50/50 pre-mix providing protection up to 150,000 miles or 5 years for AWD and RWD variants.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated, phosphate-free formula that greatly surpasses OEM standards for metallic corrosion and erosion protection.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Withstands heavy towing, elevated temperatures, and provides reserve protection during severe use.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – A cost-effective synthetic fluid that protects against wear in the 8-speed automatic transmission.
- AMSOIL SEVERE GEAR® 75W-85 100% Synthetic Gear Lube – Controls thermal runaway and reduces operating temperatures in both front and rear differentials.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures excellent ABS and traction-control responsiveness with stable viscosity over a wide temperature range.
Engine Oil Specifications and Capacities
The 2018 Genesis G90 with the 5.0L V8 engine (Engine Code [H] H) is engineered to operate efficiently with SAE 5W-20 motor oil, which is the preferred viscosity for all temperature conditions. While the engine can tolerate 5W-30, adhering to the 5W-20 specification ensures optimal fuel economy and proper lubrication during cold starts. The total fluid capacity for an oil change, including the replacement of the oil filter, is 9.7 quarts. If performing a change without a filter replacement or with a different procedure, the capacity is listed as 8.5 quarts. Regardless of the specific volume used, it is critical to check the oil level immediately after refilling to ensure the engine is properly lubricated and free from leaks. The oil drain plug torque should be secured to between 25 and 33 ft/lbs, and a new washer must always be installed on the drain bolt to prevent seepage.
For owners seeking the absolute pinnacle of engine protection, AMSOIL Signature Series 5W-20 is the top choice. This 100% synthetic formula offers 75% more protection against horsepower loss and wear compared to standard oils. It is designed to last up to 25,000 miles or one year, making it ideal for those who want to maximize the intervals between service. For those who prefer a balance of performance and economy, the Extended-Life 5W-20 provides 20,000 miles of protection with enhanced cleaning power to combat engine sludge. The OE 5W-20 is a robust synthetic option that effectively fights deposits, while the High-Mileage 5W-20 is specifically chemically treated to reduce sludge by 67% and boost performance in engines that have already surpassed 75,000 miles. Every gallon of this motor oil meets or exceeds the rigorous requirements needed for this high-performance V8.
Transmission and Differential Lubrication
The 2018 Genesis G90 features an 8-speed automatic transmission (A8TR1-1), which requires a high-quality synthetic fluid to ensure smooth shifting and longevity under heavy loads. The total fill capacity for this transmission is 9.7 quarts. To handle the rigors of heavy towing, elevated temperatures, and challenging terrain, the AMSOIL Signature Series Fuel-Efficient Automatic Transmission Fluid is highly recommended. This 100% synthetic fluid remains fluid even in sub-zero temperatures while providing reserve protection during abusive driving conditions. For owners who prefer a standard yet fully synthetic option, the OE Fuel-Efficient Automatic Transmission Fluid offers reliable protection against wear and maintains fuel efficiency. Both fluids are engineered to exceed original equipment manufacturer standards, ensuring the transmission remains responsive and durable.
The differential system in the G90 also relies on precise lubrication to manage power delivery and protect the gears from metal-to-metal contact. The front differential requires 1.5 pints of lubricant, while the rear differential requires 3 pints. Both differentials operate under GL-5 specifications and are compatible with SAE 75W-85 AMSOIL SEVERE GEAR gear lube. AMSOIL SEVERE GEAR 75W-85 is the ideal choice for this application. This 100% synthetic gear lube is formulated to control thermal runaway, a common issue in limited-slip differentials where heat buildup can degrade oil and damage gears. It contains friction modifiers specifically for limited-slip applications, reduces operating temperatures, and protects against rust and corrosion. By using this specialized fluid, you significantly extend the life of the seals, gears, and the differential assembly itself.
Cooling and Brake System Fluids
Maintaining the correct thermal balance in the 2018 Genesis G90 is essential for preventing overheating and corrosion within the cooling system. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant capacity varies by drivetrain configuration. For All-Wheel Drive (AWD) models, the system holds 12 quarts, while the Rear-Wheel Drive (RWD) variants require 12.7 quarts. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a pre-mixed ethylene glycol solution designed for a wide variety of vehicles. It is phosphate-, nitrate-, nitrite-, silicate-, borate-, and amine-free, ensuring compatibility with all other coolant colors and providing protection for up to 150,000 miles or 5 years. For those who prefer a concentrated formula, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers even greater protection, suitable for heavy-duty applications up to 1,000,000 miles or 8 years in extreme conditions. It greatly surpasses OEM standards for metallic corrosion and erosion protection while being safe for all cooling system metals, gaskets, and hoses.
Brake safety cannot be overlooked in a vehicle of the G90’s size and performance capabilities. The recommended AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is FMVSS116 DOT-3 or DOT-4. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is superior to conventional fluids because it provides excellent ABS and traction-control responsiveness. Its synthetic formulation ensures a stable viscosity over a wide temperature range, preventing the fluid from boiling under hard braking and maintaining consistent pedal feel. This stability is crucial for the safety systems of a luxury sedan like the G90, ensuring that the braking system performs reliably in every driving scenario.
About the Vehicle
The 2018 Genesis G90 stands as a testament to Hyundai’s premium division, Genesis, establishing itself as a formidable competitor in the full-size luxury sedan segment. Born from the Hyundai Motor Group, the G90 was developed to offer a driving experience and level of luxury that rivals European counterparts like the Mercedes-Benz S-Class and BMW 7 Series, often at a more accessible price point. The vehicle is a mid-size to full-size luxury sedan that emphasizes comfort, technology, and refined performance.
Under the hood, the 5.0L V8 engine provides robust power, delivering a driving character that is both smooth and potent. This engine is designed to handle high performance with ease, making the G90 a favorite for those who require long-distance comfort without sacrificing power. The platform is known for its sophisticated suspension tuning, which isolates occupants from road imperfections while maintaining a connected feel during spirited driving. The interior is typically appointed with high-quality materials, including leather upholstery, real wood trim, and advanced infotainment systems, creating an ambiance of quiet luxury.
Owners often cite the G90’s exceptional value proposition as a primary reason for its popularity, noting that it offers features standard on the G90 that are optional or exclusive to more expensive rivals. The vehicle’s reputation is built on its reliability, strong warranty coverage, and the sheer presence it commands on the road. It is designed for the executive or the family that requires a safe, spacious, and technologically advanced travel environment.
Despite its robust engineering, like any high-performance vehicle, the 2018 Genesis G90 can face specific challenges over time, particularly regarding fluid degradation and wear in extreme conditions. Using AMSOIL synthetic lubricants can help mitigate several known areas of concern for this model. First, the V8 engine can experience carbon buildup in the fuel injectors and intake valves, a condition common in direct injection and high-compression engines; regular use of AMSOIL’s fuel system cleaners and high-performance motor oils can help maintain optimal flow and combustion. Second, the automatic transmission, while generally reliable, can suffer from shift shudder or hesitation over time if the fluid degrades; high-mileage or severe-service transmission fluids can help restore shifting smoothness. Third, the cooling system can be prone to corrosion or overheating if the coolant is not changed frequently; AMSOIL Passenger Car & Light Truck Antifreeze & Coolant or AMSOIL Propylene Glycol Antifreeze and Engine Coolant can provide superior protection against rust and boil-over. Finally, brake fluid absorption of moisture over time can lead to a spongy pedal feel and lower boiling points; switching to AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid helps maintain pedal firmness and prevents corrosion in the brake lines and calipers. Addressing these areas with premium synthetic fluids ensures the G90 continues to deliver the luxury and performance experience it was designed for.