The heart of your 1987 Chevrolet Blazer is the 5.7-liter V8 engine, a legendary powerplant known for its durability. However, like all internal combustion engines, it requires consistent protection to maintain its compression and smooth operation. The recommended oil capacity for this engine, including the filter, is 5.0 quarts. It is crucial to use the correct viscosity, which is SAE 5W-30 for all operating temperatures. This grade is preferred over the 10W-30 alternative for optimal cold starts and high-temperature stability.
AMSOIL Signature Series 5W-30 stands out as the premier choice for this application. It offers 75% more engine protection against horsepower loss and wear compared to industry standards. This oil is engineered to withstand the rigors of towing, long commutes, and extreme temperature fluctuations. For owners of high-mileage Blazers, the AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil is an excellent alternative. Its unique chemistry is designed to reduce sludge by 67% and boost detergency, which helps rejuvenate older engines and control oil consumption.
Matching the oil with a high-quality filter is just as important. The AMSOIL Oil Filter provides 99% filtration efficiency at 20 microns, capturing contaminants that can cause premature wear. It offers greater capacity for small, wear-causing particles than competing filters, helping to reduce engine wear and extend service life. Alternatively, the WIX Oil Filter is a premium aftermarket choice that offers improvements over original equipment manufacturer-branded filters, ensuring that the new oil remains clean throughout its service interval.
Transmission and Transfer Case Fluids
The 1987 Blazer’s drivetrain includes either a 3-speed THM400 or a 4-speed THM700-R4 automatic transmission, both of which benefit significantly from synthetic fluid. These transmissions were originally filled with Dexron II or III, but technical service bulletins have updated specifications to Dexron VI, requiring high-performance fluid to handle the increased thermal loads. The total fill capacity for the THM400 is 10.6 quarts, while the THM700-R4 requires 11.5 quarts.
The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is engineered to withstand the specific demands of these GM transmissions. It remains fluid in sub-zero temperatures and provides reserve protection during heavy use, making it ideal for off-road enthusiasts who tow or drive on challenging terrain. The fluid resists sludge buildup and oxidation, which are common causes of harsh shifting and transmission failure in older vehicles. For a more cost-effective option that still meets or exceeds OEM requirements, the AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid provides excellent wear protection and smooth shifting characteristics.
The transfer case is another critical component, especially given the Blazer’s 4×4 capabilities. Depending on the model, it houses either an NP205 or NP208 unit, which require specific lubrication. The AMSOIL Signature Series Multi-Vehicle 100% Synthetic Automatic Transmission Fluid or the AMSOIL OE Multi-Vehicle 100% Synthetic Automatic Transmission Fluid are recommended for these units. These fluids protect against rust and corrosion while resisting thermal runaway, ensuring the transfer case operates smoothly in both wet and dry conditions.
Diffentials and Gear Lubricants
Front and rear differentials on the 1987 Blazer require high-quality gear lubricant to handle the torque and stress of 4×4 driving. The front differential typically uses 80W-90 or 75W-90 GL-5 lubricant, with a capacity of 4 pints. The rear differential varies based on the ring gear ratio, with capacities ranging from 4.2 pints for an 8.5-inch ring gear to 13.9 pints for a 12.25-inch unit.
The AMSOIL SEVERE GEAR® 80W-90 100% Synthetic Gear Lube is a top-tier choice for these applications. It contains friction modifiers for limited-slip applications and helps reduce operating temperatures, extending the life of gears and bearings. For more extreme conditions, the AMSOIL SEVERE GEAR® 75W-90 and AMSOIL SEVERE GEAR® 75W-110 100% Synthetic Gear Lube offer enhanced thermal stability and extreme pressure protection. These lubricants control thermal runaway and protect against rust and corrosion, which is vital for maintaining the integrity of the differential gears over the vehicle’s long service life.
Cooling and Brake Systems
The cooling system in the 1987 Blazer must be properly maintained to prevent overheating, especially during summer driving or heavy towing. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant capacity is approximately 17.4 quarts with air conditioning and 18.5 quarts without. This antifreeze & coolant is an excellent choice, offering protection up to 150,000 miles or 5 years. This ethylene glycol-based formula is compatible with all cooling system metals, gaskets, and hoses, and it is free of phosphates, nitrates, and silicates, ensuring compatibility with all other coolant colors.
For the braking system, the Blazer uses hydraulic DOT 3 brake fluid. The AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is designed to provide excellent ABS and traction-control responsiveness. It maintains a stable viscosity over a wide temperature range, preventing brake fade and ensuring reliable stopping power. Additionally, the power steering system benefits from AMSOIL 100% Synthetic Multi-Vehicle Power Steering Fluid, which reduces friction and helps seals remain soft to prevent leaks.
Vehicle Background
Model History and Performance
The 1987 Chevrolet Blazer represents a pivotal era in the history of American sport utility vehicles. Produced by General Motors, the Blazer was the two-door counterpart to the Chevrolet K5 Blazer, which was the four-door version. Both models were built on the GMT400 platform, which was known for its rugged durability and off-road prowess. This era of the Blazer is often celebrated for its timeless design, which featured a square-body aesthetic that has become iconic in automotive history.
Powered by the 5.7-liter V8 engine, this model offered a potent combination of power and reliability. The 5.7L engine, often referred to as the “350,” was a staple in GM’s lineup for decades. It provided sufficient torque for towing and off-roading, making the Blazer a versatile vehicle for both daily driving and recreational use. The available four-wheel-drive system, typically featuring the NP205 or NP208 transfer cases, allowed owners to tackle difficult terrain with confidence. The Blazer’s popularity during this period cemented its status as a favorite among off-road enthusiasts and collectors alike.
One of the key strengths of the 1987 Blazer is its mechanical simplicity compared to modern vehicles. This ease of maintenance has contributed to its enduring popularity, with many owners capable of performing their own repairs. However, the aging of the vehicle requires vigilant maintenance to keep it running smoothly. Regular fluid changes with high-quality synthetic lubricants can significantly extend the life of critical components, addressing common issues that arise in older vehicles.
Owners of the 1987 Blazer often report satisfaction with the vehicle’s handling and performance, particularly in off-road scenarios. The solid front axle and leaf spring suspension provide a robust ride that absorbs bumps effectively. However, this setup can also lead to specific problems over time, such as oil leaks, transmission wear, and cooling system issues. Using synthetic motor oils like AMSOIL Signature Series can help mitigate these problems by providing superior protection against wear and reducing sludge buildup. Similarly, switching to synthetic transmission fluids and gear lubes can enhance shifting smoothness and protect against the thermal stresses of off-road driving. By maintaining these fluids with high-performance alternatives, Blazer owners can ensure their vehicle remains a reliable and enjoyable companion for years to come.