The 2004 Infiniti Q45 equipped with the 4.5-liter VK45DE V8 is a sophisticated luxury sedan designed for long-distance cruising and spirited performance. To maintain the factory’s high standards for power and reliability, using the correct lubricants is essential. This engine requires specific oil viscosities to handle high temperatures and ensure rapid lubrication during cold starts. Beyond the engine, the vehicle’s automatic transmission, rear differential, cooling system, and braking components rely on specialized fluids to operate smoothly and avoid premature wear. AMSOIL synthetic lubricants provide superior protection against the sludge, heat, and thermal breakdown that can occur in this high-performance vehicle, ensuring it runs efficiently for the long haul.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – The top-tier choice offering up to 25,000 miles of protection with exceptional resistance to horsepower loss and wear.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – Provides up to 20,000 miles of protection with enhanced cleaning power to keep the engine running smoothly.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – A cost-effective synthetic option that fights sludge and deposits while delivering performance comparable to original equipment oils.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Formulated specifically for vehicles over 75,000 miles with boosted detergents to reduce sludge and protect seals.
- AMSOIL Oil Filter – Engineered for extended service life with 99% efficiency at 20 microns to capture harmful contaminants.
- WIX Oil Filter – A premium aftermarket alternative offering improvements over original equipment manufacturer-branded filters.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A pre-mixed, phosphate-free formula that protects the cooling system for up to 150,000 miles or five years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that meets rigorous corrosion standards and offers protection up to 150,000 miles.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Withstands heavy towing and high temperatures while remaining fluid in sub-zero conditions.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Delivers reliable wear protection for the 5-speed automatic transmission.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Ideal for the rear differential, providing advanced wear protection and friction modifiers for limited-slip applications.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Offers superior low-temperature fluidity and thermal control for demanding conditions.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – A heavy-duty option designed to handle extreme loads and temperatures in the rear axle.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Provides stable viscosity across a wide temperature range for excellent ABS and traction-control responsiveness.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Reduces friction and helps seals remain soft to prevent leaks while resisting heat.
The engine of the 2004 Infiniti Q45 is a formidable 4.5-liter V8, known for its smooth power delivery and robust engineering. When it comes to maintaining this powerplant, the capacity is 5.9 quarts, including the filter. The manufacturer specifies a 5W-30 viscosity grade for all temperatures, making it the preferred choice for year-round operation. While conventional oils may meet the minimum requirements, AMSOIL Signature Series and AMSOIL Extended-Life synthetic motor oils significantly outperform industry standards. For owners seeking maximum longevity, the Signature Series offers up to 25,000 miles of guaranteed protection, reducing wear and horsepower loss more effectively than standard oils. For those who prefer a balance of cost and performance, the Extended-Life or AMSOIL OE formulations provide similar synthetic benefits at different service intervals.
Proper filtration is just as critical as the oil itself. The AMSOIL Oil Filter is designed to match the performance of the oil, providing 99% filtration efficiency at 20 microns. This ensures that small, wear-causing contaminants are trapped before they can damage the engine’s internal components. The filter also features greater capacity for contaminants compared to competing brands, allowing for longer service intervals without compromising protection. For those who prefer established aftermarket brands, the WIX Oil Filter is also a recommended option, offering premium media that improves upon OEM-branded filters.
Fluid maintenance extends well beyond the engine oil. The cooling system holds 10.4 quarts of AMSOIL Passenger Car & Light Truck Antifreeze & Coolant. AMSOIL offers two primary options for this vehicle: a pre-mixed Passenger Car & Light Truck Antifreeze & Coolant or a concentrated Propylene Glycol Antifreeze. Both are designed to meet or exceed original equipment manufacturer requirements, protecting metals, gaskets, and hoses from corrosion. The unique OAT formulation used in these coolants ensures compatibility with all other antifreeze colors and provides up to five years or 150,000 miles of protection, reducing the frequency of coolant changes compared to conventional glycol-based fluids.
Transmission health is vital for the Q45’s automatic transmission (RE5R05A), which requires a total fill of 10.9 quarts. The Signature Series Fuel-Efficient Automatic Transmission Fluid is engineered to withstand the rigors of heavy towing, elevated temperatures, and challenging terrain. It remains fluid even in sub-zero temperatures, ensuring smooth shifting and protecting against wear. The AMSOIL OE Fuel-Efficient variant offers a comparable synthetic alternative for standard maintenance needs. Both fluids help maintain the transmission’s efficiency and longevity, preventing the buildup of sludge that can lead to costly repairs.
The rear differential requires specific attention as well. For the rear axle, the capacity is 3 pints of gear lubricant. The rear differential typically uses GL-5 lubricants. AMSOIL SEVERE GEAR® synthetic gear lubes in 80W-90, 75W-90, and 75W-110 viscosities provide advanced protection against wear, thermal runaway, and rust. These lubes contain friction modifiers specifically beneficial for limited-slip applications, helping to reduce operating temperatures and extend the life of the oil, seals, and equipment.
Brake and steering systems also benefit from synthetic formulations. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid ensures excellent responsiveness and stability across a wide temperature range, which is crucial for maintaining braking performance. For the power steering system, the AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid resists heat for long fluid life and helps seals remain soft to prevent leaks. These specialized fluids ensure that the vehicle’s safety-critical systems operate quietly and effectively.
Vehicle Background
The 2004 Infiniti Q45 stands as a flagship luxury sedan that exemplifies Japanese engineering at its peak. Built on the D platform, it was designed to compete directly with European luxury sedans, offering a blend of opulence and performance that was hard to beat in the early 2000s. Powered by the VK45DE V8 engine, this vehicle delivers a smooth and powerful driving experience, characterized by ample low-end torque and a refined exhaust note. The Q45 was renowned for its spacious interior, high-quality materials, and advanced features for its time, making it a favorite among those who prioritized comfort and driving dynamics.
As a top-of-the-line model for Infiniti, the Q45 was engineered for long-distance cruising. Its suspension setup provided a balanced ride, absorbing road imperfections while maintaining stability during spirited driving. The vehicle’s reputation for reliability is bolstered by its simple yet effective mechanical layout, which includes a robust 5-speed automatic transmission designed to handle the V8’s power. The Q45 represents a classic era of luxury sedans that focused on traditional mechanical excellence rather than the complex electronics of modern vehicles. Owners of this vehicle often appreciate its durability and the satisfaction of maintaining a high-performance machine with proven AMSOIL products that honor its engineering heritage.
For those who enjoy seasonal storage or long periods of inactivity, AMSOIL Gasoline Stabilizer and AMSOIL Engine Fogging Oil are available to protect internal components. Additionally, performance improvers like AMSOIL P.i. Performance Improver can help maintain fuel system cleanliness, restoring horsepower and improving fuel economy. By selecting the right AMSOIL products, owners can ensure their 2004 Infiniti Q45 continues to deliver the performance and reliability it was designed for, regardless of the mileage or driving conditions.