Keeping your 2018 Chevrolet Malibu running smoothly requires more than just basic maintenance; it demands fluids engineered to meet the specific demands of its engine. The 1.8L four-cylinder, identified by engine code LKN U, operates under conditions where precision lubrication is critical for longevity. From the initial break-in phase to high-mileage service, using the correct oil grade and viscosity ensures that internal components are protected against wear, sludge, and extreme temperatures. This guide outlines the precise lubrication specifications and product recommendations to maximize the performance and service life of your Malibu.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-20 100% Synthetic Motor Oil – Offers unsurpassed engine protection for up to 25,000 miles and shields turbochargers and high-output engines.
- AMSOIL Extended-Life 5W-20 100% Synthetic Motor Oil – Provides 37% more cleaning power and guarantees 20,000 miles of protection between changes.
- AMSOIL OE 5W-20 100% Synthetic Motor Oil – A cost-effective 100% synthetic option designed to fight sludge and deposits while matching OEM mileages.
- AMSOIL 5W-20 100% Synthetic High-Mileage Motor Oil – Formulated specifically for vehicles over 75,000 miles to reduce oil consumption and clean existing sludge.
- AMSOIL Oil Filter – Features 99% efficiency at 20 microns, a high-capacity media design to capture contaminants, and a synthetic bypass filter.
- WIX Oil Filter – A premium media option that offers improvements over original equipment manufacturer-branded filters.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An ethylene glycol pre-mix providing up to 150,000 miles of protection against corrosion and cavitation.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated formula that greatly surpasses standards for metallic corrosion protection and is safe for all cooling system metals.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Remains fluid in sub-zero temperatures and withstands the rigors of towing and elevated heat.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Protects against wear while delivering fuel economy benefits and extending service life.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Ensures excellent ABS and traction-control responsiveness with a stable viscosity range across extreme temperatures.
- AMSOIL P.i. Performance Improver – A gasoline additive that restores up to 14% horsepower and cleans fuel injectors to 100% flow rate.
Engine oil for the 1.8L engine must meet the GM Dexos1 Gen 3 specification. This specification is an update from the previous Gen 2 requirement and is critical for preventing Low-Speed Pre-Ignition (LSPI) and protecting turbochargers in modern engines. SAE 5W-20 is the preferred viscosity for this vehicle across all temperature ranges, though 0W-20 is also an acceptable alternative for extreme conditions. The engine requires a capacity of 5.3 quarts when performing a standard oil change that includes a filter replacement. After refilling, it is essential to check the oil level to ensure the correct amount is present. The oil drain plug should be torqued to 10.3 ft/lbs to prevent leaks or damage to the threads.
When selecting a filter, you have two high-quality options depending on your maintenance philosophy. The AMSOIL Oil Filter (Part EA15K35) offers extended service life and superior filtration efficiency compared to standard paper filters. For those who prefer a widely available replacement that still outperforms the original equipment, the WIX Oil Filter (Part 57674) is an excellent choice. Both filters are designed to capture wear-causing contaminants more effectively than competing filters, ensuring that the oil remains clean and the engine runs smoothly. The WIX filter is specifically compatible with housing and cap markings found on the vehicle, such as those from Hengst or UFI, ensuring a perfect seal.
While engine oil receives the most attention, the cooling system is equally vital for the longevity of the Malibu. The cooling system capacity is 7.3 quarts. The AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is an ethylene glycol, 50/50 pre-mixed formula that protects against corrosion, cavitation, and foam. It is free from phosphates, nitrates, nitrites, silicates, borates, and amines, making it safe for all metals, gaskets, and hoses in the cooling system. Alternatively, the concentrated AMSOIL Propylene Glycol Antifreeze allows for mixing with distilled water to create a custom blend. This concentrated option offers up to 150,000 miles or 5 years of protection, with heavy-duty capabilities extending to 1,000,000 miles or 8 years in appropriate applications. Both options ensure that the engine operates within its ideal temperature range, preventing overheating in summer and freezing in winter.
For the automatic transmission, proper fluid selection is crucial to maintain shift quality and prevent premature wear. The transmission requires 3.4 quarts for an initial fill and 7.1 quarts for a total fill, with a capacity code of 5ET50 for the AF6 fluid type. The AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid is designed to withstand the rigors of heavy towing, elevated temperatures, and challenging terrain. It remains fluid in sub-zero temperatures and provides reserve protection during heavy use. The AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid offers a comparable alternative with a focus on wear protection and fuel efficiency, suitable for those looking to extend the time between transmission fluid changes without sacrificing performance.
Brake fluid maintenance is another often-overlooked aspect of vehicle care. The 2018 Malibu utilizes a DOT 3 hydraulic brake fluid system. AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is formulated to provide excellent responsiveness for anti-lock braking systems (ABS) and traction control. It maintains a stable viscosity over a wide temperature range, ensuring that brake pedal feel remains consistent even under repeated hard stops or in freezing conditions. This synthetic fluid also resists moisture absorption, which can lower the boiling point of conventional fluids and lead to brake fade.
Beyond the standard fluid changes, fuel system maintenance plays a significant role in maintaining engine performance. Carbon buildup in the fuel injectors and combustion chambers can lead to reduced horsepower and poor fuel economy. The AMSOIL P.i. Performance Improver is a gasoline additive that restores up to 14% horsepower by cleaning fuel injectors and intake valves. It is compatible with capless fuel systems and helps control pre-ignition knock, which is particularly relevant for modern gasoline direct injection (GDI) engines. Additionally, for vehicles that see seasonal use or are stored for extended periods, AMSOIL Gasoline Stabilizer can keep fuel fresh for up to 12 months, preventing varnish and gum buildup. AMSOIL Engine Fogging Oil provides protection against rust for internal components during storage, making it a valuable addition for winterizing the vehicle.
About the Vehicle
The 2018 Chevrolet Malibu represents a significant entry in the mid-size sedan market, offering a blend of modern technology, fuel efficiency, and a comfortable ride quality that has become a hallmark of the model. This particular generation, which entered its second year of production, continued the evolution started in 2016, refining the design language to appeal to a younger, tech-savvy demographic while maintaining the practicality expected by fleet buyers and families. The 1.8L four-cylinder engine, specifically the LKN variant, is a naturally aspirated powerplant designed to prioritize efficiency and smooth operation over raw horsepower, making it an ideal candidate for daily commuting and fuel-conscious driving.
Owners of the 2018 Malibu typically appreciate the spacious interior, which includes a high-resolution infotainment system and a suite of driver-assistance features that were available as options or standard on higher trims. The vehicle sits on a platform designed for front-wheel drive, prioritizing a quiet cabin and a ride that absorbs road imperfections well. The 1.8L engine, producing around 135 horsepower, works in tandem with a six-speed automatic transmission to deliver smooth acceleration and predictable handling. While not a performance sedan, the Malibu is widely regarded as a sensible choice in a segment often dominated by competitors with more aggressive styling but sometimes less reliability.
Common issues reported by owners of this vehicle often relate to the longevity of engine components and the transmission system under severe service conditions. One known problem area is the development of sludge and deposit buildup in the oil pan and on the valvetrain, particularly if conventional oil intervals are followed. This sludge can restrict oil flow and lead to premature wear, which is where the use of high-quality synthetic motor oils like Signature Series or Extended-Life provides a significant advantage. Another potential issue involves the cooling system, where corrosion or clogged passages can lead to overheating. Using a high-quality, phosphate-free antifreeze can mitigate these risks and extend the life of the radiator and water pump.
Transmission hesitation or shudder is another concern that has been observed in some Malibu models, often attributed to the fluid losing its frictional properties over time. Changing to a high-mileage or synthetic automatic transmission fluid can restore proper friction characteristics, leading to smoother shifts and reduced wear on clutch plates. Additionally, some owners have reported issues with carbon buildup in the intake valves, a common characteristic of modern GDI engines, which can lead to rough idling and reduced fuel economy. Periodic use of a fuel system cleaner like the AMSOIL P.i. Performance Improver can help mitigate these deposits and restore engine performance.
By addressing these potential weak points with the correct synthetic lubricants, 2018 Malibu owners can ensure their vehicles remain reliable and efficient for years to come. The 1.8L engine, when properly cared for with the recommended fluids, demonstrates the durability and low-maintenance nature that Chevrolet designed into the Malibu. It is a vehicle that rewards proactive maintenance with a quiet, comfortable, and economical driving experience. Whether you are looking to extend the service intervals or simply maintain the vehicle according to strict standards, using the specified AMSOIL products ensures that every aspect of the car’s mechanical systems is protected against the wear and tear of daily driving.