2018 GMC Sierra 1500 Fluid Type Specs

As a DIYer or professional technician, using the correct fluids is critical for the longevity and performance of any vehicle. This guide provides a comprehensive list of the factory-specified fluids and capacities for the 2018 GMC Sierra 1500. Always double-check your owner's manual or OEM service information to confirm specs for your specific configuration.

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil (4.3L V6)	SAE 5W-30 Full Synthetic (dexos1 Gen 2)	6.0 qt / 5.7 L
Engine Oil (5.3L V8 & 6.2L V8)	SAE 0W-20 Full Synthetic (dexos1 Gen 2)	8.0 qt / 7.6 L
Engine Coolant	ACDelco Dex-Cool OAT (GM 6277M)	16.5 qt - 17.4 qt / 15.6 L - 16.5 L
Automatic Transmission Fluid	ACDelco Dexron VI Full Synthetic	11.2 qt - 12.2 qt / 10.6 L - 11.5 L
Transfer Case Fluid	ACDelco Dexron VI	1.6 qt / 1.5 L
Front Differential (4WD)	SAE 75W-90 Synthetic Gear Oil (GM 9986115)	1.8 qt / 1.7 L
Rear Differential	SAE 75W-85 Synthetic Gear Oil (GM 19300457)	2.75 qt / 2.6 L
Brake Fluid	DOT 3	As needed
Power Steering Fluid	ACDelco Power Steering Fluid (GM 19329450)	As needed
Windshield Washer Fluid	Good quality solvent	~1.0 gal / 3.8 L

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Engine Oil

For the 2018 model year, GMC specifies full synthetic engine oils that meet the dexos1 Gen 2 specification. Using a non-licensed oil can lead to engine sludge, reduced fuel economy, and potential warranty claim denials.

• 4.3L V6 LV3 EcoTec3: Requires SAE 5W-30 full synthetic oil meeting dexos1 Gen 2. Capacity with filter change is 6.0 quarts (5.7 liters).
• 5.3L V8 L83 & 6.2L V8 L86 EcoTec3: Requires SAE 0W-20 full synthetic oil meeting dexos1 Gen 2. The 0W-20 viscosity is mandatory for proper operation of the engine's complex systems, including the Active Fuel Management (AFM). Capacity with filter change is 8.0 quarts (7.6 liters).

Notes: The dexos1 Gen 2 specification was a significant update designed to combat Low-Speed Pre-Ignition (LSPI) in modern turbocharged, direct-injection engines. While the Sierra's engines were not all turbo, the spec provides superior deposit and sludge protection. Do not use heavier oils like 10W-30 or 15W-40, as they can impede oil flow and affect the hydraulic solenoids that control AFM and variable valve timing.

Engine Coolant

Your Sierra 1500 was factory-filled with a silicate-free, orange-colored Organic Acid Technology (OAT) coolant. The specific GM specification is GM 6277M, sold under the ACDelco Dex-Cool brand.

• System Capacity: Varies by engine and cooling package, typically between 16.5 and 17.4 quarts (15.6 to 16.5 liters) for an initial fill.

Notes: It is critical to use only a compatible OAT coolant. Never mix Dex-Cool with conventional green (IAT) or hybrid (HOAT) coolants, as this can cause the coolant to gel, leading to blockages in the radiator, heater core, and coolant passages, resulting in severe engine overheating. When servicing, use a 50/50 mixture of Dex-Cool concentrate and distilled water. The service interval is typically 5 years or 150,000 miles, but always check for discoloration or contamination.

Transmission Fluid

All 2018 Sierra 1500 trucks, whether equipped with the 6-speed or 8-speed automatic transmission, require a full synthetic fluid that meets the Dexron VI specification.

• Fluid Type: ACDelco Dexron VI Full Synthetic Automatic Transmission Fluid.
• Capacity: Varies greatly. A simple drain-and-fill may replace 5-6 quarts, while a full system overhaul requires 11.2 to 12.2 quarts (10.6 to 11.5 liters). There is no dipstick for a casual check; fluid level must be checked via the fill plug on the side of the transmission case at a specific operating temperature.

Notes: Dexron VI is NOT a "universal" ATF. Do not use fluids labeled as "multi-vehicle" or older Dexron specifications like Dexron III. Dexron VI is a low-viscosity fluid with a specific friction profile designed for the clutch packs and solenoids in modern GM transmissions. Using the wrong fluid can cause harsh shifts, shuddering, and eventual transmission failure.

Drivetrain Fluids (4WD)

Transfer Case

For four-wheel-drive models, the transfer case also uses automatic transmission fluid, which simplifies service.

• Fluid Type: ACDelco Dexron VI.
• Capacity: Approximately 1.6 quarts (1.5 liters).

Differentials

• Front Differential: Requires SAE 75W-90 Synthetic Gear Oil meeting GM specification 9986115. Capacity is approximately 1.8 quarts (1.7 liters).
• Rear Differential: Requires SAE 75W-85 Synthetic Gear Oil, GM part number 19300457. Capacity is approximately 2.75 quarts (2.6 liters). Unlike some limited-slip differentials, a friction modifier additive is generally not required for the factory G80 locking differential.

Brake Fluid

General Motors specifies a standard DOT 3 motor vehicle brake fluid for the 2018 Sierra 1500. While DOT 4 fluid has a higher boiling point and is compatible, it is also more hygroscopic (absorbs moisture faster) and is not required.

Notes: Never use DOT 5 silicone-based fluid, as it is incompatible with the seals and ABS module in a DOT 3 system. Brake fluid should be flushed every 2-3 years, regardless of mileage, due to moisture absorption which can corrode internal brake components and reduce stopping power.

Power Steering Fluid

The 2018 Sierra 1500 uses an electric power steering (EPS) system on most models, which does not use any fluid. However, for models equipped with hydraulic power steering, a specific fluid is required.

• Fluid Type: ACDelco Power Steering Fluid (GM Part No. 19329450). Do not use generic power steering fluid or automatic transmission fluid.

Windshield Washer Fluid

Use any good quality, commercially available windshield washer solvent. In colder climates, ensure the fluid has adequate freeze protection.

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