Maintaining the 1980 Plymouth Volare with its 3.7-liter inline-six engine requires more than just filling a tank; it demands a disciplined approach to fluid selection. This classic M-body sedan, powered by the 225 cubic inch engine, has a specific lubrication profile that can be easily overlooked by modern standards. Using the correct viscosity and formulation is essential to prevent wear, manage the engine’s thermal output, and preserve the longevity of the transmission and differential components. Whether the vehicle is used for daily commuting on rough roads or sits as a restoration project, the internal components need protection that exceeds the limitations of conventional mineral oils.
Recommended AMSOIL Products
For the 1980 Plymouth Volare 3.7L, AMSOIL offers a complete line of synthetic lubricants designed to handle the demands of this vintage powertrain while providing superior protection against the wear and tear associated with older engines.
- AMSOIL Signature Series 10W-30 100% Synthetic Motor Oil – This top-tier oil offers unsurpassed protection against horsepower loss and wear, providing up to 25,000 miles of service intervals for drivers who demand the absolute best.
- AMSOIL Extended-Life 10W-30 100% Synthetic Motor Oil – A robust choice for extended service intervals, this oil features enhanced cleaning power to keep the engine running smoothly for up to 20,000 miles.
- AMSOIL OE 10W-30 100% Synthetic Motor Oil – Outperforming conventional oils while meeting OEM mileage requirements, this formulation fights sludge and deposits effectively with its 100% synthetic base.
- AMSOIL 10W-30 100% Synthetic High-Mileage Motor Oil – Specifically engineered for vehicles with over 75,000 miles, this oil includes boosted detergents and enhanced anti-wear additives to reduce sludge and improve performance.
- AMSOIL Oil Filter – Designed for maximum protection, this filter provides 99 percent efficiency at 20 microns and allows for lower restriction to keep engine parts properly lubricated.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol formulation that protects cooling system metals, gaskets, and hoses while offering protection for up to 150,000 miles or 5 years.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Capable withstanding heavy towing and elevated temperatures, this fluid remains fluid in sub-zero conditions and protects against sludge buildup.
- AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – This fluid guards against leaks and promotes smooth, shudder-free shifts while protecting against wear and resisting harmful sludge.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – Ideal for standard differentials, this lube contains friction modifiers for limited-slip applications and helps control thermal runaway.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – A versatile gear lube that provides advanced protection against wear and rust while reducing operating temperatures.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensuring excellent ABS and traction-control responsiveness, this fluid maintains a stable viscosity over a wide temperature range.
- AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid – Formulated for quiet operation, this fluid reduces friction and helps seals remain soft to prevent leaks while resisting heat for a long fluid life.
Essential Engine Oil and Filtration
The heart of the 1980 Volare is the 3.7-liter (225 cubic inch) inline-six engine. For this specific powerplant, the factory specified a capacity of 5.0 quarts when performing a complete drain and filter change. Maintaining this level is critical, as the oil drain plug requires a torque of 20 ft/lbs to ensure a proper seal without damage. While the engine is robust, it is not immune to the breakdown of conventional lubricants over time, especially in vehicles that may have accumulated significant mileage or sit for long periods.
Selecting the right viscosity is paramount. For the 3.7L engine, AMSOIL recommends 10W-30 across a wide range of operating temperatures. Below -18°C, or for cold climates, lighter weights like 5W-30 or 5W-40 can be utilized, while higher temperatures may call for 10W-40, 10W-50, or 15W-40. However, the 10W-30 grade remains the versatile standard for this engine family, whether it is used for short trips or highway driving.
The AMSOIL Signature Series 10W-30 stands out as the premier choice for this vehicle. Its advanced additive package provides 75% more engine protection against horsepower loss and wear compared to industry standards. For drivers extending the time between services, the 25,000-mile guaranteed protection offers peace of mind that the engine internals remain coated in a film that resists shear breakdown. Conversely, the AMSOIL 10W-30 High-Mileage is uniquely suited for Volare units that have surpassed 75,000 miles. Its chemistry includes seal conditioners and anti-wear additives that help reduce sludge by 67%, ensuring older seals do not harden and the engine breathes cleanly.
Filtration is just as critical as the oil itself. The AMSOIL Oil Filter (EAO42-EA) is a direct-fit replacement that allows lower restriction, ensuring oil flow remains steady even under high-pressure conditions. With a filtration efficiency of 99 percent at 20 microns, it captures small, wear-causing contaminants more effectively than standard filters, significantly reducing engine wear over the life of the vehicle.
Transmission and Transfer Case Lubrication
The 1980 Plymouth Volare was often paired with the A904 three-speed automatic transmission or various three- and four-speed manual transmissions. Maintaining these units requires specific attention to fluid volume and quality. For the A904 automatic transmission with a lockup converter, the total fill capacity is approximately 8.6 to 8.8 quarts, while an initial fill requires about 4 quarts. Manual transmissions vary by model, with capacities ranging from 4.6 pints to 7 pints, and fill plug torque settings of 15 ft/lbs and drain plug torque of 25 ft/lbs.
To protect these aging gearsets, the AMSOIL Signature Series Multi-Vehicle Automatic Transmission Fluid is the recommended choice. It withstands the rigors of heavy towing and elevated temperatures, which can be a stressor for older hydraulic systems. The fluid remains fluid in sub-zero temperatures, ensuring smooth operation during cold starts. For those seeking a more cost-effective yet still high-performance option, the AMSOIL OE Multi-Vehicle offers excellent cold-weather performance and guards against leaks and sludge, promoting shudder-free shifts.
Differential and Gear Lube
The rear differential on the Volare requires a robust gear lube to handle the loads placed on the ring and pinion gears. Depending on the specific axle configuration, capacities can range from 2.1 pints to 4.4 pints. The standard requirement is typically a GL-5 rating, with viscosity grades of 80W-90 or 90 for moderate temperatures.
For these components, the AMSOIL SEVERE GEAR® 80W-90 is an excellent choice. It contains friction modifiers essential for limited-slip differentials and helps control thermal runaway, which is a common failure point in older differentials under heavy loads. The lube protects against rust and corrosion while extending the life of seals and equipment. For environments with extreme cold, the AMSOIL SEVERE GEAR® 75W-90 offers superior pumpability without sacrificing protection, and the 75W-110 grade provides an even heavier viscosity for specific high-load applications.
Coolant, Brake, and Power Steering Systems
Preventing overheating is vital for the longevity of the 3.7L engine. With air conditioning, the cooling system capacity is 13.3 quarts, and without, it is 11.6 quarts. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a 50/50 pre-mix formulation that protects all cooling system metals, gaskets, and hoses. It is phosphate, nitrate, nitrite, silicate, borate, and amine-free, making it safe for a wide variety of vehicle components and compatible with other antifreeze colors. For those who prefer a concentrated mix, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers protection up to 150,000 miles or 5 years.
The braking and steering systems also benefit from AMSOIL’s synthetic formulations. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is recommended for the hydraulic brake system. It provides excellent responsiveness for ABS and traction control systems while maintaining stability over a wide temperature range, preventing boil-off during heavy braking. For the power steering system, the AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid reduces friction and helps seals stay soft to prevent leaks. It is formulated for quiet operation, ensuring that the steering mechanism remains smooth and responsive throughout its service life.
About the Vehicle
Introduced by Chrysler Corporation in 1976, the 1980 Plymouth Volare was a cornerstone of the brand’s strategy to regain market share in the compact and intermediate car segments. Part of the extensive “K-car” and “A-body” lineage, the Volare represented a significant evolution from the classic Plymouth Satellite, blending a more aerodynamic design with the rugged utility expected of an American sedan. In 1980, the vehicle was in the midst of its production run, a period where the brand was aggressively competing against Japanese imports by offering reliable, spacious, and affordable transportation options to American families.
The specific 1980 model year Volare featured in this guide is equipped with the 3.7L (225 cubic inch) inline-six engine, identified by engine code [C]. This naturally aspirated six-cylinder was a staple of the Plymouth lineup for decades, known for its durability and smooth power delivery. While it did not match the horsepower figures of modern turbocharged engines, the 3.7L was celebrated for its ability to pull heavy loads and maintain performance in demanding conditions. The engine’s straightforward design, combined with the vehicle’s sturdy chassis, made it a favorite for those who prioritized reliability over raw speed. Owners of this vehicle often value the Volare for its spacious interior, which offered ample passenger room and cargo capacity, a feature that was highly regarded in the early 1980s. The car’s legacy is one of practicality and enduring strength, making it a worthy candidate for careful maintenance and restoration today.
Additional Maintenance and Care
Beyond the core lubrication needs, proper maintenance of the 1980 Plymouth Volare involves attention to fuel quality and general upkeep. For drivers who use their vehicle for seasonal storage, the AMSOIL Gasoline Stabilizer helps keep fuel fresh for up to 12 months, preventing varnish and gum buildup that can clog fuel systems. If the engine is to be stored for extended periods, the AMSOIL Engine Fogging Oil provides a rust preventive coating for internal components.
To ensure peak performance, the AMSOIL P.i. Performance Improver can be used to clean fuel injectors and restore lost horsepower. For general vehicle care, the AMSOIL Synthetic Multi-Purpose Grease resists thermal degradation, making it ideal for chassis components and wheel bearings. Finally, keeping the vehicle clean with the AMSOIL Miracle Wash Waterless Wash and Wax Spray provides a protective finish that repels dust and dirt while shielding the paint from UV rays.