Maintaining the fluid integrity of a 1987 Mitsubishi Pickup with the 2.6-liter 4-cylinder engine (Engine Code [E] E) is essential for preserving its mechanical longevity. These vehicles were designed for durability, but their internal components, particularly in the engine and drivetrain, face significant wear over decades of operation. Proper lubrication ensures that moving parts remain protected against friction, heat, and contamination. Whether the truck is used for daily commuting, off-road recreation, or stored for the winter, using the correct fluids prevents sludge buildup, corrosion, and excessive wear that can lead to costly repairs. The 2.6L engine, while robust, requires specific viscosity grades to ensure optimal oil pressure and flow across the full range of operating temperatures.
Recommended AMSOIL Products
For owners seeking the highest level of protection, AMSOIL offers a comprehensive lineup of synthetic lubricants tailored to the specific needs of this vehicle. The following products address the engine, cooling, transmission, and differential requirements, ensuring your Pickup operates at peak performance.
- AMSOIL Signature Series 10W-30 100% Synthetic Motor Oil – Provides 75% more engine protection against horsepower loss and wear compared to industry standards, offering the ultimate defense for your 2.6L engine.
- AMSOIL Extended-Life 10W-30 100% Synthetic Motor Oil – Delivers 37% more cleaning power to help keep the engine running smoother and offers guaranteed protection for up to 20,000 miles between changes.
- AMSOIL OE 10W-30 100% Synthetic Motor Oil – Fights sludge and deposits with a 100% synthetic formulation that delivers reliable protection at a value price point.
- AMSOIL 10W-30 100% Synthetic High-Mileage Motor Oil – Formulated specifically for vehicles over 75,000 miles with boosted detergents to clean internal deposits and reduce sludge by 67%.
- WIX Oil Filter – Features premium media that offers improvements over original equipment manufacturer-branded filters, ensuring superior contaminant capture to protect engine longevity.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol 50/50 pre-mix formulation that protects cooling system metals, gaskets, and hoses for up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option requiring mixing with water, offering superior corrosion protection and extended service intervals for up to 150,000 miles.
- AMSOIL 75W-90 Manual Transmission & Transaxle Gear Lube – Friction-modified fluid with excellent seal compatibility and outstanding cold-flow properties to protect brass synchronizers and inhibit rust.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Provides excellent ABS and traction-control responsiveness with stable viscosity over a wide temperature range for safer stopping power.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Designed for differentials with advanced protection against wear and thermal runaway, containing friction modifiers for limited-slip applications.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Controls operating temperatures and protects against rust and corrosion, ideal for front and rear differentials needing GL-5 protection.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – Offers a higher viscosity option for demanding conditions, providing long oil and seal life with friction modifiers for limited-slip differentials.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Withstands 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 guards against leaks, promoting smooth, shudder-free shifts for automatic transmissions.
Engine Oil and Filtration Requirements
The 2.6-liter 4-cylinder engine in the 1987 Mitsubishi Pickup is the heart of this vehicle. To ensure it continues to run smoothly, it is critical to select the correct viscosity grade based on your local climate. For temperatures below 16°C, SAE 5W-20 is an option, though it is not recommended for sustained high speeds. For moderate conditions, 10W-30 is a primary recommendation. In hotter climates above 0°C, 10W-40, 10W-50, or 20W-40 grades are suitable. The engine holds 5.2 quarts of oil when the filter is replaced. It is vital to check the oil level after refilling and to torque the oil drain plug to between 26 and 32 ft/lbs to prevent leaks or stripped threads.
Filter selection is equally important. The WIX Oil Filter (Part Code 51381) is the recommended unit for this application. Its premium media captures contaminants more effectively than many OEM-branded filters, extending the life of the oil and the engine itself. Using a high-quality filter ensures that abrasive particles do not circulate back into the engine block, which is particularly important for older engines that may have accumulated minor wear particles over the years.
Transmission and Drivetrain Lubrication
The drivetrain of the Mitsubishi Pickup varies depending on whether it is a rear-wheel drive or 4-wheel drive model, and whether it has a manual or automatic transmission. For manual transmissions, the capacity differs slightly. The RWD model holds 4.9 pints, while the 4WD model holds 4.6 pints. Both require GL-4 lubricant with a viscosity of 75W-85W or 80W. AMSOIL 75W-90 Manual Transmission & Transaxle Gear Lube is an excellent choice here, as it protects brass synchronizers and provides excellent seal compatibility, which is crucial for preventing leaks in aging manual units.
Automatic transmissions require a different approach. While the vehicle may originally have called for specific Dexron fluids, AMSOIL’s Signature Series Multi-Vehicle ATF or OE Multi-Vehicle ATF offers superior thermal stability and friction control. These fluids are designed to resist sludge and ensure smooth shifting even under the load of towing or heavy hauling. The fluid must be changed periodically to maintain the integrity of the valve bodies and clutches.
The transfer case on 4WD models requires GL-4 lubricant, with a capacity of 4.6 pints. For the front and rear differentials, GL-5 lubricants are specified. The front differential requires 4.6 pints, while the standard rear differential needs 2.7 pints. If the vehicle is equipped with a limited-slip differential (LSD), it requires 3.2 pints and must use an oil designated for limited-slip applications. The AMSOIL SEVERE GEAR® line covers these requirements perfectly, with options in 80W-90 and 75W-90 viscosities that handle the extreme pressure of gear engagement and protect against rust and corrosion.
Cooling, Braking, and Other Fluids
The cooling system in this vintage Pickup has a capacity of 8.5 quarts. Keeping the engine at the proper temperature is non-negotiable for preventing head gasket failures and warped components. AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a 50/50 pre-mix that exceeds original equipment requirements and is phosphate, nitrite, and borate-free. For those preferring concentrated coolant, AMSOIL Propylene Glycol Antifreeze offers extended service intervals and compatibility with all coolant colors.
Hydraulic brake fluid is another critical maintenance item. The system utilizes DOT 3 hydraulic brake fluid. Over time, brake fluid absorbs moisture, which lowers its boiling point and can lead to brake fade or corrosion in the master cylinder and calipers. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid resists this moisture absorption and maintains stable viscosity across a wide temperature range, ensuring consistent brake pedal feel and responsiveness. Similarly, the power steering system requires an automatic transmission fluid that meets Dexron-II standards, which the AMSOIL automatic transmission fluids handle exceptionally well.
Vehicle Background
The 1987 Mitsubishi Pickup represents a significant era in the history of compact trucks in the United States and globally. Part of the first generation of Mitsubishi trucks sold under the “Mitsubishi L200” nameplate in export markets (known as the “Mitsubishi Truck” or “Mitsubishi 4×4” in the US), these vehicles were known for their rugged simplicity and reliability. The 2.6-liter SOHC inline-four engine, codenamed “E” or “E-E,” was Mitsubishi’s primary offering for the American market during this period. It was a robust, overhead-valve design that prioritized torque and low-end power over high-RPM horsepower, making it ideal for hauling cargo and navigating rough terrain.
Owners of this vehicle often praise its utilitarian nature. The 1987 model year was a period where manufacturers were transitioning from purely utilitarian designs to vehicles with more comfort features, yet the Pickup retained its core identity as a workhorse. The platform was versatile, available in 2-wheel drive for highway use and 4-wheel drive for off-road capability. The 4WD system was a part-time setup that required manual engagement, a characteristic that many off-road enthusiasts appreciated for its durability and simplicity. The truck’s suspension was tuned for load-bearing capacity, allowing it to carry heavy payloads without sagging excessively, a trait that made it a favorite among farmers, contractors, and outdoor enthusiasts.
Despite their durability, owners of the 1987 Mitsubishi Pickup often encounter a few specific maintenance challenges that AMSOIL synthetic lubricants can help mitigate. First, the 2.6L engine is susceptible to oil consumption and piston ring wear as it ages. Using a synthetic high-mileage motor oil with enhanced anti-wear additives and detergents can help seal gaps and clean out carbon deposits that contribute to excessive oil burning. Second, the manual transmission can develop synchro chatter or grinding, particularly in the first or second gear, due to the hardening of seals over time. A high-quality GL-4 gear lube helps lubricate these components and prevents the grinding sensations that occur when synchros are worn.
Third, the transfer case in 4WD models can suffer from fluid leaks at the seals, leading to low lubrication levels and potential failure of the transfer chain or gears. Synthetic gear lubes like AMSOIL SEVERE GEAR® maintain their viscosity better than conventional oils, providing a more robust seal and reducing the rate of seal hardening. Finally, the cooling system in these older vehicles often develops leaks or corrosion in the radiator and water pump due to years of exposure to rust and old coolant. An OAT (organic acid technology) antifreeze like AMSOIL’s Passenger Car & Light Truck Antifreeze & Coolant is highly compatible with a variety of metal types and older seal materials, helping to prevent corrosion and extending the life of the entire cooling system.
By addressing these specific points with the right lubricants, owners can restore much of the truck’s original performance and reliability. The 1987 Mitsubishi Pickup remains a beloved vehicle for those who value mechanical simplicity and the ability to handle tough jobs without complex electronics. With the proper AMSOIL fluids, the mechanical heart of the 2.6L engine and the drivetrain components can continue to serve owners faithfully for years to come.