The 1998 Mitsubishi Eclipse equipped with the 2.4L 4-cylinder engine (Engine Code G, 4G64 G) is a performance-oriented vehicle that demands precise maintenance to sustain its power and longevity. Using the correct lubricants is essential not just for reducing engine wear, but also for maintaining the thermal efficiency required by the engine’s design. For this specific model year and displacement, the manufacturer recommends SAE 5W-30 motor oil, with 10W-30 acceptable in temperatures above -18°C. Ensuring the proper capacity is maintained, specifically 4.5 quarts when changing the AMSOIL Oil Filter, helps optimize the engine’s internal lubrication and cooling performance. Whether the vehicle is used for spirited weekend driving or daily commuting, the right fluid selection protects against horsepower loss, sludge formation, and extreme temperature fluctuations.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – Delivers unsurpassed engine protection, offering up to 25,000 miles of performance and significant improvements in wear protection against horsepower loss.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – Provides extended protection for up to 20,000 miles with enhanced cleaning power to keep the engine running smoother for longer intervals.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – A reliable choice that outperforms conventional oils and fights sludge, serving as a high-quality synthetic alternative to original equipment specifications.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Specifically formulated for vehicles exceeding 75,000 miles to reduce sludge, lower oil consumption, and boost detergent performance.
- AMSOIL Oil Filter – Offers filtering efficiency of 99 percent at 20 microns, allowing lower restriction and reduced engine wear compared to standard filters.
- WIX XP Oil Filter – Features premium media that offers improvements over original equipment manufacturer-branded filters, ensuring superior contaminant capture.
- WIX Oil Filter – A solid choice featuring premium media designed to exceed OEM filter standards for optimal engine protection.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – A unique poly-organic acid formulation providing up to 150,000 miles of protection without harmful silicates or borates.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option for superior corrosion and erosion protection, reaching up to 1,000,000 miles in heavy-duty applications.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Designed to withstand heavy towing, elevated temperatures, and challenging terrain while remaining fluid in sub-zero conditions.
- AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Resists harmful sludge and promotes smooth, shudder-free shifts with excellent cold-weather performance.
- WIX Transmission Filter – Premium media construction that outperforms OEM filters to ensure clean fluid flow for the transmission system.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures excellent ABS and traction-control responsiveness with stable viscosity across a wide temperature range.
- AMSOIL 75W-90 Manual Transmission & Transaxle Gear Lube – Protects brass synchronizers and offers outstanding cold-flow properties for long service life.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Advanced protection against wear and thermal runaway, containing friction modifiers for limited-slip differentials.
- AMSOIL 75W-90 Long Life 100% Synthetic Gear Lube – Engineered for extended service life with improved seal life and better cold-weather shifting capabilities.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – Provides heavy-duty protection for severe service conditions with superior thermal control and wear resistance.
Proper fluid maintenance extends far beyond the engine crankcase, encompassing the entire drivetrain and braking systems of your Eclipse. The cooling system requires specific attention, as the 2.4L engine relies on a robust antifreeze mixture to maintain optimal operating temperatures. With a capacity of 7.4 quarts, the cooling system needs a fluid that prevents corrosion and overheating. AMSOIL’s passenger car antifreeze offers a phosphate-free, silicate-free solution that protects all metals, gaskets, and hoses for up to 150,000 miles or five years. This prevents the degradation of antifreeze and coolant that can lead to costly radiator and water pump failures. For those requiring a more concentrated solution, the Propylene Glycol Antifreeze allows for mixing with distilled water to achieve extended service intervals and superior heat transfer properties.
Transmission and Drivetrain Protection
For the automatic transmission, the fluid must handle the torque demands of the Eclipse’s powertrain while maintaining smooth shift quality. The recommended fluid capacity is 4 quarts for the initial fill, and using a synthetic fluid ensures consistent performance during heavy towing or spirited driving. The Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid is engineered to remain fluid even in sub-zero temperatures while resisting oxidation during high-heat events. It provides reserve protection during abusive conditions, ensuring the transmission shifts are smooth and shudder-free. The AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid serves as a cost-effective alternative that still guards against leaks and harmful sludge buildup, promoting the longevity of the transmission’s internal components. A compatible WIX Transmission Filter further enhances this protection by removing contaminants that could affect valve body operation.
The differential and transfer case lubrication is equally critical for handling the power delivered to the wheels. While specific transfer case requirements may vary by trim, general maintenance guidelines recommend using high-quality gear lubes to handle the pressure and friction inherent in 4WD systems. The AMSOIL 75W-90 Manual Transmission & Transaxle Gear Lube is an excellent choice for synchronizer protection and rust inhibition. For applications requiring more extreme pressure protection, the SEVERE GEAR® 75W-90 and 75W-110 synthetic gear lubes offer advanced thermal runaway control. These fluids contain friction modifiers beneficial for limited-slip differentials and help reduce operating temperatures, extending the life of seals and gears. The 75W-90 Long Life 100% Synthetic Gear Lube is another option designed for extended service intervals, offering improved efficiency and seal compatibility.
Brake System and Fuel Care
Brake safety is paramount, and the hydraulic brake system for the Eclipse utilizes DOT 3 compatible fluid. AMSOIL’s DOT 3 and DOT 4 100% Synthetic Brake Fluid provides a stable viscosity that resists boiling, ensuring consistent pedal feel and rapid response in ABS and traction-control systems. This synthetic formulation prevents the moisture absorption and vapor lock common in conventional brake fluids, which can lead to brake fade. Additionally, for owners looking to maximize engine performance and fuel economy, fuel additives play a vital role. The AMSOIL P.i.® Performance Improver restores up to 14% horsepower and cleans GDI fuel injectors to 100% flow rate after a single tank of treated fuel. This helps prevent carbon buildup and controls pre-ignition knock, ensuring the engine runs efficiently. The AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor further supports the fuel system by lubricating upper cylinders and the fuel system components.
About the Vehicle
The 1998 Mitsubishi Eclipse belongs to a lineage of sport coupes that have long been favorites among automotive enthusiasts. This specific model year sits at the tail end of the second generation (GS model), a period known for its distinct wedge-shaped bodywork and aggressive styling cues. Powered by the reliable 2.4L 4-cylinder engine, the 4G64 G, this vehicle offers a balance of everyday drivability and spirited performance. The engine family is renowned for its durability, though it was also the base for the more powerful turbocharged variants found in the GS-T and RS models of the era. The 2.4L naturally aspirated version provides a solid foundation for handling and tuning, making it a popular choice for owners who enjoy modifying their vehicles or simply want a fun, lightweight coupe.
The Eclipse is celebrated for its front-engine, front-wheel-drive layout, which delivers predictable handling characteristics. Owners of the 1998 model often appreciate the blend of Japanese engineering reliability and American-market muscle car aesthetics. The interior design of this era emphasized a driver-focused cockpit, with controls and instrumentation placed for easy access. Whether driven on highway commutes or on local back roads, the Eclipse offers a dynamic driving experience that distinguishes it from the more conservative sedans of the late 90s. Its reputation as a versatile performance machine has kept it relevant in the used car market, with enthusiasts valuing its potential for upgrades and its solid build quality. Regular maintenance, particularly focusing on the engine and fluid systems discussed, is key to keeping this classic sport coupe in top condition for years to come.
Additional Maintenance and Care Products
Beyond the essential lubricants, a comprehensive maintenance regimen includes products that protect the vehicle during storage or harsh conditions. AMSOIL offers a gasoline stabilizer that helps keep fuel fresh for up to 12 months, ideal for seasonal storage or vehicles that do not see frequent use. For engine protection during long periods of inactivity, the AMSOIL Engine Fogging Oil provides a heavy-duty rust preventive coating for internal components. When it comes to cleaning and protection, the Heavy-Duty Degreaser effectively removes tough grease and grime from engine bays, while the AMSOIL Silicone Spray protects rubber surfaces and locks out moisture without attracting dirt. Exterior care is also important; the Miracle Wash Waterless Wash and Wax Spray leaves a protective finish that repels dust, and the AMSOIL Exterior Ceramic Spray offers rapid water shedding and UV protection. These products, when used in conjunction with high-quality fluids, ensure the vehicle remains in peak operational and cosmetic condition.