The 1980 Subaru BRAT is a unique piece of automotive history, featuring a distinctive 1.8-liter flat-four engine that requires specific attention to detail for optimal longevity. Proper lubrication is critical for this vehicle, as the EA81 engine design relies on precise fluid properties to manage wear, heat, and efficiency. Using the wrong viscosity or an inferior fluid can lead to premature engine wear, poor fuel economy, and costly repairs. This guide outlines the exact fluid capacities, specifications, and recommended products to ensure your Subaru BRAT operates smoothly for years to come.
Recommended AMSOIL Products
- AMSOIL Signature Series 10W-30 100% Synthetic Motor Oil – Offers the highest level of protection against wear and horsepower loss, ideal for extending oil intervals up to 25,000 miles.
- AMSOIL Extended-Life 10W-30 100% Synthetic Motor Oil – Provides exceptional cleaning power and 20,000 miles of guaranteed protection for routine maintenance.
- AMSOIL OE 10W-30 100% Synthetic Motor Oil – An OEM-mileage fluid formulated to fight sludge and deposits while outperforming conventional oils.
- AMSOIL 10W-30 100% Synthetic High-Mileage Motor Oil – Specifically designed for engines with over 75,000 miles, featuring enhanced anti-wear additives and improved seal conditioners.
- AMSOIL Oil Filter – Delivers 99% efficiency at 20 microns with reduced restriction to keep engine parts lubricated and reduce wear.
- WIX Oil Filter – A premium alternative offering superior filtration media compared to many original equipment manufacturer brands.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol pre-mix that provides protection for up to 150,000 miles or 5 years while protecting cooling system metals and hoses.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated formula offering up to 150,000 miles of protection with superior corrosion and erosion resistance.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Designed to withstand heavy towing, elevated temperatures, and sub-zero conditions without losing viscosity.
- AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Provides smooth, shudder-free shifts and guards against leaks and sludge buildup.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – A versatile gear oil for manual transmissions and differentials that controls thermal runaway and rust.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Offers advanced protection for high-load applications with excellent cold-weather performance.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – An extra-heavy viscosity gear lube ideal for demanding differentials and limited-slip applications.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures excellent ABS responsiveness and stable viscosity over a wide temperature range.
Maintaining the 1980 Subaru BRAT requires a precise understanding of its fluid capacities and the specific roles each fluid plays in keeping the flat-four engine and drivetrain healthy. For the engine, the capacity is 3.7 quarts when including the oil filter change. This amount ensures the oil pump can circulate enough lubricant to coat all critical components, from the pistons to the crankshaft bearings. Filling beyond the recommended capacity can cause foaming and increased pressure, while under-filling leaves components vulnerable to metal-to-metal contact. It is essential to torque the oil drain plug to 29-33 ft/lbs and check the oil level with a dipstick after refilling.
The transmission system on the 1980 BRAT varies depending on the configuration. For automatic transmissions, a total fill requires 7.6 quarts, while an initial fill needs 2.6 quarts. This fluid is critical for hydraulic pressure regulation and clutch engagement. For manual transmissions, the capacity is approximately 6.3 pints for 4WD models and 5.7 pints for other configurations, requiring a torque of 30-35 ft/lbs on the drain plug. The differential system also needs attention, with the front differential (for automatic transmission models only) holding 2.5 pints and the rear differential holding 1.7 pints. Using a high-quality synthetic gear lube in these areas protects the gears from wear, prevents rust, and reduces operating temperatures.
Cooling the engine is just as important as lubricating it, especially for a vehicle of this vintage. AMSOIL offers two primary coolant options. The Passenger Car & Light Truck Antifreeze & Coolant is a pre-mixed, phosphate- and silicate-free formula that protects all cooling system metals. Alternatively, the Propylene Glycol Antifreeze and Engine Coolant is a concentrated formula that allows for precise mixing and offers extended service life. Both options ensure that the 1.8-liter engine remains within its safe operating temperature range, preventing overheating and head gasket failures common in older Subaru engines.
Beyond the essential fluids, several additives and maintenance products can further extend the life of this classic vehicle. AMSOIL P.i.® Performance Improver Gasoline Additive can restore up to 14% horsepower by cleaning fuel injectors and reducing carbon buildup. For seasonal storage, the Gasoline Stabilizer helps keep fuel fresh for up to 12 months, while the Engine Fogging Oil protects internal components from rust during long periods of inactivity. Additionally, the Upper Cylinder Lubricant Corrosion Inhibitor lubricates the fuel system and upper cylinders, ensuring smooth operation and reduced wear.
About the Vehicle
The 1980 Subaru BRAT, which stands for “BiDrive Recreational All-terrain Transporter,” is a unique chapter in automotive history. Unlike many of its contemporaries that focused solely on traditional pickup truck utility or sedan efficiency, the BRAT offered a distinctive blend of both, wrapped in a compact package that captured the imagination of car enthusiasts and families alike. Powered by the robust 1.8-liter EA81 flat-four engine, this vehicle was known for its reliability and ability to handle a variety of conditions, from city streets to unpaved country roads.
What set the BRAP apart from the start was its innovative design that included rear-facing “jump seats” in the bed area, allowing the vehicle to be legally classified as a passenger car in some markets despite its pickup-like appearance. This quirky feature, combined with Subaru’s legendary symmetrical all-wheel-drive system (on 4WD models), gave the BRAT a level of traction and versatility that was unmatched in its class during the early 1980s. The flat-four engine, positioned low in the chassis, provided a low center of gravity that contributed to stable handling characteristics, making it a favorite for those who enjoyed driving as much as utility.
Subaru’s reputation for durability was well-established even in 1980, and the BRAT benefited from this engineering philosophy. The boxer engine design minimized vibration and improved balance, which was particularly appreciated by drivers who took the vehicle on longer journeys. Over the years, the BRAT has cultivated a cult following, with owners often praising its durability and unique charm. While it may not have offered the raw power of some larger American trucks, its efficiency and all-weather capability made it a practical and beloved choice for a generation of drivers. Today, these vehicles are cherished by collectors and enthusiasts who appreciate a time when automotive design dared to be different.