Based on the specific engineering requirements of the 2004 Infiniti FX35, the following lubricants are recommended to ensure optimal protection for your vehicle’s drivetrain and cooling systems.
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – Offers the highest level of engine protection, suitable for extreme driving conditions and extended oil change intervals up to 25,000 miles.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – Provides a balance of protection and value with guaranteed performance for up to 20,000 miles between changes.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – Designed to outperform conventional oils while meeting original equipment manufacturer mileage standards, ideal for regular maintenance.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Specifically formulated for engines with over 75,000 miles to reduce oil consumption and sludge while protecting seals.
- AMSOIL Oil Filter – Engineered with premium filtration media to capture contaminants and ensure proper oil flow, featuring a 99% filtration efficiency at 20 microns.
- WIX Oil Filter – A premium aftermarket option that offers superior media improvements over standard OEM-branded filters for critical engine protection.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A pre-mixed ethylene glycol formula that protects cooling system metals and hoses for up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated non-toxic option requiring mixing, offering superior thermal protection and longevity for the engine cooling system.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Provides extreme durability against heavy towing, high temperatures, and harsh terrain, ensuring smooth shifts and reserve protection.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Offers reliable protection against wear and sludge while promoting smooth, shudder-free gear changes.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Ideal for front and rear differentials, providing advanced wear protection and thermal control for limited-slip applications.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – A versatile heavy-duty lubricant that helps reduce operating temperatures and extends the life of seals and equipment.
- 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.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Formulated to reduce friction, keep seals soft to prevent leaks, and resist heat for long fluid life.
Proper lubrication is the single most important factor in maintaining the reliability of the Infiniti FX35. The VQ35DE engine is known for its smooth power delivery, but like all high-performance naturally aspirated engines, it requires oil that can withstand the heat generated during spirited driving or heavy loads. AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil is the premium choice for those who drive aggressively, tow frequently, or operate the vehicle in extreme cold or hot weather. This synthetic oil provides 75% more engine protection against horsepower loss and wear compared to leading conventional oils. For owners of vehicles with higher mileage, the AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil uses unique chemistry to condition seals and reduce oil consumption, effectively helping engines last longer and perform better.
The transmission in the 2004 FX35, specifically the RE5R05A 5-speed automatic, benefits significantly from synthetic fluid. Standard transmission fluids can break down under the stress of shifting and elevated temperatures, leading to shuddering or harsh gear changes. AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid and AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid remain fluid in sub-zero temperatures while withstanding the rigors of heavy towing and challenging terrain. This ensures that the transmission’s internal components are protected from wear, while also offering the benefit of reduced friction, which can contribute to better fuel economy.
When it comes to the cooling system, the 2004 Infiniti FX35 requires a specific type of antifreeze to protect its aluminum components. AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a poly-organic acid (OAT) formulation that exceeds OEM requirements. It is phosphate-, nitrate-, and silicate-free, making it safe for all cooling system metals, gaskets, and hoses. For those who prefer a concentrated solution, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers similar long-life benefits with the added advantage of non-toxicity.
The differential and transfer case lubricants play a crucial role in the FX35’s all-wheel-drive system. The front and rear differentials require high-quality gear lube to handle the loads and prevent wear. AMSOIL SEVERE GEAR 80W-90 100% Synthetic Gear Lube is ideal for these applications, providing advanced wear protection and thermal control. The AMSOIL SEVERE GEAR 75W-90 100% Synthetic Gear Lube is a versatile heavy-duty lubricant that helps reduce operating temperatures and extends the life of seals and equipment. Both formulations contain friction modifiers specifically for limited-slip applications, ensuring smooth operation of the differential while extending the life of the equipment.
Beyond the major mechanical fluids, maintaining the FX35 involves attention to smaller but critical systems. The brake fluid in this vehicle should be replaced with a high-performance synthetic alternative to ensure consistent pedal feel and responsiveness. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides a stable viscosity over a wide temperature range, which is vital for safety during emergency stops or repeated braking. Similarly, the power steering system benefits from the AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid, which resists heat and helps seals remain soft to prevent leaks, ensuring quiet and responsive steering operation.
For those who engage in seasonal storage, protecting the fuel system is paramount. The use of AMSOIL Gasoline Stabilizer can keep fuel fresh for up to 12 months, protecting against varnish and gum buildup and fighting ethanol corrosion. Additionally, AMSOIL P.i. Performance Improver is a highly effective gasoline additive that restores up to 14% horsepower and improves fuel economy by cleaning fuel injectors and combustion chambers. These additives, combined with regular filter changes using premium AMSOIL or WIX filters, ensure that the 2004 Infiniti FX35 remains a reliable and powerful machine year after year.
Vehicle Background
The 2004 Infiniti FX35 represents a significant chapter in the history of luxury crossovers. Launched in 2003 as the successor to the Infiniti QX4, the FX series introduced the world to a new vehicle segment that combined the handling of a sports car with the utility of an SUV. The 2004 model, featuring the 3.5-liter VQ35DE engine, became an instant favorite among driving enthusiasts for its balanced character and sophisticated design. Based on the Nissan F-platform, the FX35 was engineered to offer a sportier driving experience than traditional boxy SUVs of the time, with a lower center of gravity and responsive suspension tuning.
The VQ35DE engine, a member of Nissan’s renowned VQ engine family, was celebrated for its smooth power delivery, high-revving capability, and durability. With around 260 to 270 horsepower depending on the specific tuning of the model year, the 3.5L V6 provided ample acceleration for a vehicle of its size, making it a favorite for those who enjoyed spirited driving on winding roads or needed the power for highway merging and towing. The FX35 was one of the first crossover utility vehicles to offer a rear-wheel-drive bias that could be distributed to the front wheels as needed, giving drivers confidence in various weather conditions without sacrificing the “fun-to-drive” factor.
Infiniti positioned the FX35 in a competitive market against emerging luxury crossovers, distinguishing itself through its premium interior appointments, advanced safety features, and refined ride quality. The vehicle’s sleek, wedge-shaped design and luxurious cabin set a new standard for the segment, appealing to drivers who wanted more than just a practical family hauler. Over the years, the FX series has gained a reputation for reliability and enduring value, with many 2004 models still on the road today thanks to robust engineering and proper maintenance. For owners of this vehicle, keeping up with high-quality fluid maintenance is key to preserving its unique blend of luxury and performance.