Maintaining the 1981 Porsche 928 4.5L requires precise fluid selection to ensure the longevity of its unique 8-cylinder engine and transmission system. This vehicle demands synthetic lubricants that can handle extreme temperatures and provide superior protection against wear, as mineral-based oils are not sufficient for the engine’s operational requirements. Proper lubrication reduces friction, minimizes sludge buildup, and ensures that the cooling and braking systems function reliably over the vehicle’s lifespan. For owners seeking the best possible protection, AMSOIL offers a comprehensive range of synthetic products specifically tested to meet or exceed the rigorous standards required by this classic sports sedan.
Recommended AMSOIL Products
- AMSOIL 5W-40 FS 100% Synthetic European Motor Oil – A specialized formula designed for the precise demands of European vehicles, featuring a blend of synthetic base oils and premium additives for optimal engine protection.
- AMSOIL 5W-40 MS 100% Synthetic European Motor Oil – Another top-tier option tailored for European engines, providing a precise blend that ensures stability and protection across all operating temperatures.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol 50/50 pre-mix formulation that protects cooling system metals, gaskets, and hoses while offering extended service life.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated solution that requires mixing, offering superior corrosion protection and long-lasting performance for passenger cars and light trucks.
- AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid – Formulated 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 – Provides excellent cold-weather performance, resists sludge, and promotes smooth, shudder-free shifts for automatic transmissions.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Delivers advanced protection against wear and thermal runaway, with friction modifiers suitable for limited-slip applications.
- AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube – Provides robust protection against rust and corrosion, helping to reduce operating temperatures and extend equipment life.
- AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube – A versatile option for various gear applications, featuring advanced protection against wear and rust.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Offers excellent responsiveness for ABS and traction control systems with a stable viscosity over a wide temperature range.
The engine of the 1981 Porsche 928 is a critical component that requires specific attention to fluid viscosity and composition. The manufacturer specifies a capacity of 8.5 quarts when including the filter. It is important to note that synthetic oil is required for this engine to ensure proper lubrication under high-stress conditions. For those operating in varying climates, the 5W-40 viscosity is ideal for all temperatures, while 5W-50 is also suitable for any condition. In colder regions where temperatures drop below 38°C, a 5W-30 grade is recommended, whereas above -10°C, 15W-40 or 15W-50 mineral-based options exist, though the synthetic European formulas provide superior coverage. After refilling the system, owners should always check the oil level to ensure the engine is properly filled and ready for operation.
Proper cooling system maintenance is equally vital for the longevity of this vehicle’s powertrain. The cooling system holds a capacity of 16.9 quarts of fluid. Using the correct antifreeze and coolant formulation helps prevent corrosion and ensures efficient heat transfer. The recommended AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a poly-organic acid (OAT) formulation compatible with all cooling system metals, gaskets, and hoses. It is phosphate, nitrate, nitrite, silicate, borate, and amine-free, offering protection for up to 150,000 miles or 5 years. Alternatively, the Concentrated Propylene Glycol Antifreeze allows for mixing with distilled water, extending protection to 150,000 miles or 5 years in passenger applications. Both options safeguard the engine against freezing and overheating while maintaining the integrity of the cooling system components.
Transmission health is another area where fluid choice significantly impacts performance and durability. For the automatic transmission (G28/05) with code 722.1, the total fill capacity is 6.3 quarts, while the initial fill capacity is 5.8 quarts. The vehicle also utilizes a manual transmission (G28/05, 5-speed) that requires 8 pints of fluid. To meet these requirements, the AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid offers robust protection against wear, sludge, and leaks, ensuring smooth shifts even under heavy loads. The OE Multi-Vehicle option provides a cost-effective alternative with excellent cold-weather performance. For the manual transmission and differential, the SEVERE GEAR line of synthetic gear lubes is essential. The 75W-90 grade is suitable for general use, while 75W-110 and 80W-90 provide specific viscosity characteristics for different applications. These gear lubes contain friction modifiers for limited-slip applications and help control thermal runaway, ensuring the differential and transmission operate smoothly in extreme conditions.
Fluid maintenance extends beyond the engine and transmission to include critical safety systems like braking. The 1981 Porsche 928 requires a hydraulic brake fluid meeting DOT 4 TYPE 200 standards. Using the AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid ensures stable viscosity over a wide temperature range, providing excellent responsiveness for anti-lock braking systems and traction control. This synthetic formulation does not absorb moisture as quickly as conventional fluids, maintaining consistent performance over time. For power steering, which operates on a Dexron-III equivalent fluid, the multi-vehicle synthetic automatic transmission fluid can be used effectively, offering the same protective qualities required for steering reliability. These fluids ensure that braking and steering systems remain responsive and safe, regardless of driving conditions.
About the Vehicle
The 1981 Porsche 928 represents a significant chapter in the brand’s history, marking the company’s bold entry into the grand touring segment with a front-engine, rear-wheel-drive layout. At the heart of this iconic sports sedan lies the impressive 4.5-liter V8 engine, known for its smooth power delivery and high-revving capabilities. Unlike the mid-engine layout of the legendary 911, the 928 utilized a longitudinal V8, a design choice that offered excellent weight distribution and a spacious interior, setting it apart as a luxury cruiser capable of blistering performance.
Developed to challenge the dominance of competitors like the Aston Martin and Jaguar, the 928 was designed from the ground up to combine everyday usability with sports car dynamics. The 4.5L engine produced substantial horsepower, allowing for effortless high-speed cruising and impressive acceleration. Its water-cooled design was advanced for the era, ensuring the engine stayed cool during long tours or spirited driving sessions. The vehicle’s reputation is built on its blend of comfort and performance, often described as a “Porsche 911 for the road” due to its refined ride quality and sophisticated handling characteristics.
Owners of the 1981 model year appreciate the 928 for its unique character and engineering excellence. The 4.5-liter engine, with its specific code 8111H, is a robust unit that, with proper maintenance, can deliver reliable performance for decades. The car’s design emphasized precision and durability, features that are still highly sought after by collectors and enthusiasts today. While it may lack the mid-engine agility of a 911, the 928 offers a distinct driving experience characterized by linear power, a quiet cabin, and a commanding presence on the road. Its legacy as one of Porsche’s most sophisticated vehicles continues to attract drivers who value both classic European design and exceptional engineering.
Essential Care for Storage and Seasonal Use
For owners who may store their 1981 Porsche 928 during off-seasons, specific products can help preserve the vehicle’s condition. The AMSOIL Gasoline Stabilizer is effective at keeping fuel fresh for up to 12 months, preventing varnish and gum buildup that can clog fuel systems. Additionally, the Engine Fogging Oil provides a protective barrier for internal engine components, preventing rust during long periods of inactivity. These additives are ideal for seasonal equipment, ensuring that the vehicle is ready to run smoothly when the season returns.
Maintaining the appearance of the 928 is just as important as mechanical upkeep. The AMSOIL Miracle Wash Waterless Wash and Wax Spray offers a convenient way to clean and protect the exterior without soap or water, leaving a fantastic shine and a tough protective finish. For deeper cleaning, the Engine Degreaser and Heavy-Duty Degreaser remove tough grime from engine surfaces and other components. The Silicone Spray is useful for protecting rubber components and preventing them from cracking or drying out, ensuring that seals and hoses remain pliable and effective.
Regular maintenance with the recommended AMSOIL products ensures that the 1981 Porsche 928 4.5L continues to perform at its peak. By using high-quality synthetic lubricants, owners can extend the life of their engine, transmission, and other critical systems. The comprehensive range of AMSOIL fluids provides the necessary protection for all driving conditions, from extreme temperatures to long-distance touring. With proper care and the right lubricants, this classic vehicle can continue to deliver the refined driving experience it was designed to provide.