Maintaining your 1998 Ford Explorer with the 4.0L 6-cylinder engine requires more than just following a standard schedule; it demands fluids specifically engineered for the demands of this robust powerplant. Proper lubrication is critical for preventing wear, managing the heat generated by the high-stress 4.0L engine, and ensuring the longevity of both the transmission and the drivetrain components. Whether you are navigating city traffic, hauling cargo, or driving in extreme weather conditions, selecting the right synthetic oils and filters can make a significant difference in performance and reliability.
Recommended AMSOIL Products
For the 1998 Ford Explorer 4.0L, AMSOIL offers a range of premium synthetic motor oils designed to exceed the performance of conventional brands. The following products are the top recommendations for keeping your engine running smoothly.
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – The top-tier choice offering unsurpassed engine protection for up to 25,000 miles or one year, providing significantly more protection against horsepower loss and wear.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – A premium option delivering extended performance with 37% more cleaning power to help keep the engine running smoother for up to 20,000 miles.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – An excellent choice that outperforms conventional oils while offering protection comparable to the original equipment manufacturer specifications.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Formulated specifically for vehicles with over 75,000 miles, featuring boosted detergents and reduced sludge to help older engines perform better.
- AMSOIL Oil Filter – Provides superior filtering efficiency and greater capacity for small contaminants, helping to reduce engine wear and extend service life compared to standard filters.
Once you have selected your engine oil, it is equally important to choose the right filter to ensure maximum filtration efficiency. The AMSOIL Oil Filter (EAO15) allows for lower restriction and keeps engine parts properly lubricated by removing wear-causing contaminants. Alternatively, for those who prefer a high-quality aftermarket filter, the WIX Oil Filter (51515) offers premium media that improves over original equipment manufacturer filters. Both options ensure your synthetic oil performs at its peak.
Transmission and Drivetrain Fluids
The 1998 Ford Explorer’s 4.0L engine is often paired with automatic transmissions that require fluids capable of withstanding heat and heavy loads. Proper transmission fluid is vital for maintaining smooth, shudder-free shifts and protecting against wear. For the 5-speed RWD 5R55E and 4WD 5R55E transmissions, AMSOIL offers several highly rated options. The AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid is ideal for heavy towing and elevated temperatures, remaining fluid even in sub-zero conditions. For a budget-conscious option without sacrificing quality, the AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid provides excellent cold-weather performance and guards against leaks. If fuel economy is a priority, the AMSOIL Signature Series Fuel-Efficient and AMSOIL OE Fuel-Efficient variants are also available.
For transfer cases, which are crucial for 4WD operation, the vehicle specifies Mercon LV compatible fluids. The AMSOIL Signature Series Fuel-Efficient and AMSOIL OE Fuel-Efficient automatic transmission fluids are recommended here to ensure proper lubrication for both full-time 4WD and Warner 4405 transfer cases. Additionally, the differential gears require specific gear lubricants to handle the stress of the Explorer. The front differential typically calls for 80W-90 GL-5 fluid, while the rear standard differential also utilizes 80W-90 GL-5. For limited-slip differentials, a synthetic 75W-140 is required. AMSOIL SEVERE GEAR 80W-90 and AMSOIL SEVERE GEAR 75W-90 lubricants offer advanced protection against wear and thermal runaway, while the AMSOIL SEVERE GEAR 75W-140 variant is specifically designed for limited-slip applications to prevent chatter and ensure smooth operation.
Cooling System and Brake Fluid
Maintaining the cooling system is essential for the longevity of the 4.0L engine, which can run hot under certain conditions. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant (ANTPC) capacity for this vehicle is approximately 7.8 quarts. It is a unique poly-organic acid (OAT) formulation that provides protection for up to 150,000 miles or five years. It is phosphate-free and compatible with all other antifreeze colors. For those who prefer a concentrated solution, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers similar long-life protection and requires mixing with distilled water.
AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is another critical fluid that should never be overlooked. The vehicle recommends DOT 3 fluid. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid provides excellent responsiveness for ABS and traction control systems, maintaining a stable viscosity across a wide temperature range. This ensures consistent braking performance even under heavy load or in extreme weather.
Maintenance Kits and Additional Fluids
To simplify your maintenance routine, AMSOIL offers pre-configured oil change kits that pair the recommended motor oils with the appropriate filters. These kits are designed to save you money compared to buying items individually. Whether you choose the Signature Series, Extended-Life, OE, or High-Mileage motor oil, each kit includes the necessary AMSOIL or WIX oil filter to ensure your vehicle is protected from the moment the oil is changed.
For seasonal storage, or if the vehicle is used for specific tasks like snowmobiling or off-roading, additional AMSOIL products can be beneficial. The AMSOIL Gasoline Stabilizer helps keep fuel fresh for up to 12 months, preventing varnish and gum buildup. For vehicles that sit for long periods, AMSOIL Engine Fogging Oil can be used to protect internal engine components from rust. Fuel system health can be improved with the AMSOIL P.i. Performance Improver, which restores injectors and horsepower, while the AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor adds a layer of protection to the fuel system.
About the Vehicle
The 1998 Ford Explorer represents a pivotal era for the mid-size SUV market, continuing a legacy of rugged utility and family-friendly capability that began when the model was introduced in 1990. By the late 1990s, the Explorer had firmly established itself as a dominant player, appealing to owners who needed a versatile vehicle for both daily commuting and outdoor adventures. The specific model in question, equipped with the 4.0L SOHC 6-cylinder engine (Engine Code [E] E), is a testament to Ford’s engineering during that period, balancing power with relative reliability.
This generation of the Explorer was built on the Ford Ranger platform, which gave it a reputation for solid durability. The 4.0L engine is known for its ample low-end torque, making it well-suited for towing light trailers or hauling cargo around town. Unlike the later V8 models, the 6-cylinder variant often appealed to drivers seeking a fuel-efficient alternative without sacrificing the essential four-wheel-drive capability that defines the Explorer nameplate. Its interior was spacious by the standards of the late 90s, offering a comfortable ride for families while retaining the capability to handle light off-road trails or snowy mountain passes.
Owners of this vehicle often appreciate its straightforward mechanical design, which makes it a popular candidate for DIY maintenance and upgrades. The availability of aftermarket parts and the robust nature of the chassis have kept many of these vehicles on the road long after their warranty periods expired. While it lacks the modern technological features of contemporary SUVs, the 1998 Explorer is valued for its timeless design and the driving confidence provided by its four-wheel-drive system. It remains a reliable choice for those who value mechanical simplicity and the ability to traverse various terrains with ease.