Maintaining your 2018 GMC Sierra 1500 Pickup with the 4.3L V6 engine requires more than just following the basic maintenance schedule; it demands the use of fluids specifically formulated to handle the demands of modern truck ownership. Whether you are towing heavy loads, navigating off-road trails, or simply commuting daily in stop-and-go traffic, the longevity of your powertrain depends on the quality of lubrication it receives. This engine, known as the LV3, is a reliable workhorse, but like all internal combustion engines, it relies heavily on oil to manage heat, reduce wear, and maintain cleanliness. Using the correct AMSOIL synthetic lubricants ensures that every component, from the turbochargers to the transmission gears, operates within its optimal parameters, providing protection that exceeds industry standards.
Recommended AMSOIL Products
- AMSOIL Signature Series 5W-30 100% Synthetic Motor Oil – The ultimate choice for maximum protection, this oil offers 75% more engine protection against horsepower loss and wear, extending service intervals up to 25,000 miles. It is ideally suited for this engine due to its superior resistance to shear and extreme temperatures.
- AMSOIL Extended-Life 5W-30 100% Synthetic Motor Oil – A premium option providing 37% more cleaning power to help keep the engine running smoother for longer, with a guaranteed protection interval of up to 20,000 miles.
- AMSOIL OE 5W-30 100% Synthetic Motor Oil – Designed to outperform conventional oils and meet the rigorous GM dexos1 Gen 2 specification, offering trusted protection for up to 15,000 miles with excellent resistance to LSPI.
- AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil – Specifically formulated for vehicles with over 75,000 miles, this oil features enhanced anti-wear additives and a boosted detergent package to reduce sludge and combat oil consumption.
- AMSOIL Oil Filter – A high-capacity filter providing 99% efficiency at 20 microns, designed to allow lower restriction and keep engine parts lubricated while capturing smaller contaminants than competing filters.
- WIX XP Oil Filter – A premium aftermarket filter featuring media that offers significant improvements over original equipment manufacturer-branded filters for enhanced engine protection.
- WIX Oil Filter – A high-quality standard filter utilizing premium media to improve upon OEM filtration performance, ensuring reliable contaminant removal.
- WIX Air Filter – Features premium media that offers improvements over original equipment manufacturer-branded filters, ensuring optimal airflow and engine breathing.
- AMSOIL Passenger Car & Light Truck Antifreeze & Coolant – An exclusive poly-organic acid (OAT) formulation that protects all cooling system metals, gaskets, and hoses, offering protection up to 150,000 miles or 5 years.
- AMSOIL Propylene Glycol Antifreeze and Engine Coolant – A concentrated option that greatly surpasses standards for metallic corrosion and erosion, ideal for those preferring to mix their own antifreeze solution.
- AMSOIL Signature Series Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Engineered to withstand the rigors of heavy towing and elevated temperatures, this fluid remains fluid in sub-zero conditions and provides reserve protection during heavy use.
- AMSOIL OE Fuel-Efficient 100% Synthetic Automatic Transmission Fluid – Provides robust protection against wear while meeting OE requirements, ensuring smooth shifting and extended transmission life.
- AMSOIL SEVERE GEAR® 75W-90 100% Synthetic Gear Lube – Offers advanced protection against wear and thermal runaway, with friction modifiers that are ideal for limited-slip differentials and long equipment life.
- AMSOIL SEVERE GEAR® 75W-85 100% Synthetic Gear Lube – Perfect for axles requiring GM P/N 19300457 synthetic lubricant, this fluid helps reduce operating temperatures and protects against rust and corrosion.
- AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid – Delivers excellent ABS and traction-control responsiveness with stable viscosity across a wide temperature range, ensuring consistent braking performance.
- AMSOIL P.i.® Performance Improver Gasoline Additive – A potent additive that restores up to 14% horsepower and cleans fuel injectors to 100% flow rate, helping to control pre-ignition knock and improve fuel economy.
Optimal Lubrication for the 4.3L Engine
The heart of your 2018 GMC Sierra 1500 is the 4.3L 6-cylinder engine with code LV3. This powerplant is designed for efficiency and durability, but it still demands high-performance lubrication to operate smoothly under all conditions. The factory recommendation points to a 5W-30 viscosity, which AMSOIL has refined into four distinct product lines to suit various driving needs and vehicle ages.
For the owner who drives aggressively or tows frequently, the AMSOIL Signature Series 5W-30 is the top-tier solution. It is proven to offer significant protection against horsepower loss and wear, allowing for extended drain intervals of up to 25,000 miles. The oil’s superior shear stability ensures that it maintains its viscosity even when the engine is under heavy load, protecting critical components like the camshaft and crankshaft bearings. If your driving is a mix of highway and city, the AMSOIL Extended-Life 5W-30 offers a balanced approach with enhanced cleaning power to keep sludge and deposits at bay, extending the service interval to 20,000 miles. For those who prefer to stick closer to standard maintenance schedules, the AMSOIL OE 5W-30 provides OEM-level performance that meets or exceeds GM dexos1 Gen 2 requirements. Finally, for trucks with significant mileage, the AMSOIL 5W-30 100% Synthetic High-Mileage Motor Oil contains special additives to reduce sludge by 67% and help control oil consumption, keeping older engines running smoother.
It is crucial to remember that the engine requires 6.0 quarts of oil, including the filter. After refilling, it is essential to check the oil level to ensure the proper quantity is reached. The oil drain plug should be torqued to 18 ft/lbs to prevent leaks or thread damage. Whether you are using E85 or M85 fuels, the recommended oil viscosity should be maintained, and extended oil drains should only be attempted through oil analysis in those specific cases.
Transmission, Cooling, and Differential Care
Protecting the powertrain extends far beyond the engine oil pan. The 2018 Sierra 1500 utilizes an automatic transmission that can suffer from heat degradation over time, especially during towing. The AMSOIL Signature Series Fuel-Efficient Automatic Transmission Fluid is formulated to withstand the high temperatures and heavy loads associated with truck use. It remains fluid in sub-zero temperatures and provides a reserve of protection during abusive driving conditions. Alternatively, the AMSOIL OE Fuel-Efficient Automatic Transmission Fluid offers excellent wear protection that meets OEM specifications for the 6L80 transmission.
Cooling is vital for the longevity of the engine, particularly in the hot summer months or during long hauls. The cooling system capacity for this vehicle is 16 quarts. For those who want a hassle-free solution, the AMSOIL Passenger Car & Light Truck Antifreeze & Coolant is a 50/50 pre-mix that protects all cooling system metals and is free of silicates, borates, and phosphates that can harm modern engines. If you prefer a concentrated formula, the AMSOIL Propylene Glycol Antifreeze and Engine Coolant offers protection up to 150,000 miles or 5 years and greatly surpasses standards for corrosion resistance.
The differential and transfer case also require specific attention. For the front differential, 3 pints of AMSOIL SEVERE GEAR® 75W-90 are recommended. This heavy-duty lubricant contains friction modifiers and controls thermal runaway, extending the life of the seals and gears. For the rear differential, the requirements vary by axle size. The 8.6 RG and 9.5 RG axles, as well as the 9.76 RG, require 75W-85 AMSOIL SEVERE GEAR® 75W-85 gear lube. This fluid meets the requirements for GM P/N 19300457, ensuring compatibility and superior protection against rust and corrosion. The transfer case, depending on the model (MP 1222, 25, 26, or MP3023, 24), typically requires 3.2 pints of the same high-performance gear lubricant.
AMSOIL DOT 3 and DOT 4 100% Synthetic Brake Fluid is another critical safety component that is often overlooked. The fluid is designed to provide stable viscosity over a wide temperature range, ensuring that your ABS and traction-control systems respond instantly. It is the ideal replacement for the recommended GM P/N 19353126.
Recommended AMSOIL Products
- AMSOIL Gasoline Stabilizer – Essential for seasonal storage, this additive helps keep fuel fresh for up to 12 months and fights ethanol corrosion.
- AMSOIL Upper Cylinder Lubricant Corrosion Inhibitor – A specialized lubricant that protects the fuel system and upper cylinders, compatible with capless fuel systems.
For drivers looking to maximize fuel economy and engine performance, the AMSOIL P.i.® Performance Improver is a powerful additive. It can restore up to 14% horsepower and clean fuel injectors to 100% flow rate after just one tank of fuel. This is particularly beneficial for GDI engines, helping to reduce the need for higher-octane fuel and controlling pre-ignition knock.
About the Vehicle
The 2018 GMC Sierra 1500 Pickup is a cornerstone of the truck market, continuing a legacy that dates back to 1999 when the GMT800 platform was launched. Over the years, the Sierra 1500 has evolved into a sophisticated full-size pickup truck that balances heavy-duty capability with a high level of refinement. It is designed for a wide range of owners, from farmers who need to haul livestock to families who require a vehicle capable of pulling a boat or a camper for weekend getaways.
Equipped with the 4.3L V6 engine, known as the EcoTec3 LV3, this vehicle offers a balanced approach to power and efficiency. While the larger V8 options in the lineup provide more raw towing power, the V6 serves as an economical choice that still delivers the torque and responsiveness needed for daily tasks. The 2018 model year brought various updates and refinements, including advanced connectivity options like the onboard Wi-Fi hotspot and the infotainment system that allows for seamless integration with smartphones via Apple CarPlay and Android Auto. The interior of the Sierra 1500 is known for its spacious cabin and comfortable seating, making it a popular choice for long highway drives.
The platform is renowned for its ruggedness, featuring a fully boxed frame that provides excellent torsional rigidity. This structural integrity contributes to the truck’s ability to handle challenging terrain while maintaining a smooth ride quality that rivals many crossover SUVs. The suspension system, whether it is the standard rear coil spring setup or the available air suspension, is tuned to provide stability and comfort. The Sierra 1500 also boasts a class-leading towing capacity and payload rating, making it a versatile tool for both work and play.
Despite its reliability, the 2018 GMC Sierra 1500 does have a few known issues that owners should be aware of. One common problem involves the engine oil dilution, particularly with the V8 models, but the V6 can also experience issues where fuel mixes with the oil, potentially diluting it and reducing lubrication. This is where the use of high-quality synthetic oil becomes critical, as AMSOIL formulations are resistant to fuel dilution and can help maintain proper viscosity even in these conditions.
Another potential issue is related to the transmission, specifically the 6-speed automatic. Some owners have reported rough shifting or delayed engagement, which can be exacerbated by degraded transmission fluid. Switching to a premium synthetic transmission fluid like the AMSOIL Signature Series Fuel-Efficient Automatic Transmission Fluid can help smooth out shifts and extend the life of the transmission components. Additionally, the engine oil filter may occasionally suffer from premature failure or bypass valve issues if not replaced with a high-quality filter. The AMSOIL Oil Filter is designed with a higher capacity for contaminants and a robust construction that reduces the risk of bypass failure.
Corrosion is a third concern, particularly in regions where road salt is used during the winter. The undercarriage and frame can be susceptible to rust if not properly protected. Applying an undercoat or using a metal protector like the AMSOIL Heavy-Duty Metal Protector can provide a barrier against salt, moisture, and chemical corrosion, preserving the structural integrity of the vehicle for years to come. Finally, the fuel system in direct injection engines can accumulate carbon deposits on the intake valves over time, which can lead to reduced performance and rough idling. Regular use of a fuel system cleaner like AMSOIL P.i. can help maintain optimal fuel delivery and engine performance, ensuring that the 4.3L engine continues to run smoothly and efficiently. By addressing these common issues with proactive maintenance and high-quality lubricants, owners can enjoy their Sierra 1500 for a long and trouble-free life.