2018 GMC Yukon Fluid Type Specs

Quick Reference

Fluid	Type/Spec	Capacity
Engine Oil (5.3L V8 L83)	0W-20 ACDelco dexos1 Gen 2	8.0 qt (7.6 L)
Engine Oil (6.2L V8 L86)	0W-20 ACDelco dexos1 Gen 2	8.0 qt (7.6 L)
Engine Coolant	ACDelco DEX-COOL (Orange)	16.2 qt (15.3 L)
Automatic Transmission (6L80)	DEXRON-VI	12.4 qt (11.7 L)
Automatic Transmission (10L80)	DEXRON ULV	11.5 qt (10.9 L)
Transfer Case	DEXRON-VI	1.6 qt (1.5 L)
Front Differential	75W-90 Synthetic Gear Oil	~1.7 qt (1.6 L)
Rear Differential	75W-90 Synthetic Gear Oil	~2.75 qt (2.6 L)
Brake Fluid	DOT 3	As needed
Power Steering	Power Steering Fluid	As needed
Windshield Washer	Good quality washer fluid	As needed

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Engine Oil

The 2018 GMC Yukon, equipped with either the 5.3L or 6.2L V8 engine, requires a high-quality full synthetic oil that meets General Motors' stringent dexos1 Gen 2 specification. The required viscosity is SAE 0W-20.

• Specification: GM dexos1® Gen 2 Full Synthetic
• Viscosity: SAE 0W-20
• Capacity (5.3L & 6.2L): 8.0 quarts (7.6 liters) with filter change.

Notes: Using an oil that meets the dexos1 Gen 2 spec is critical for the longevity of these direct-injection engines. It provides superior protection against low-speed pre-ignition (LSPI), deposit formation, and wear. Always use a new oil filter with every oil change. While many brands meet the spec, ACDelco is the OEM supplier. The oil change interval can be guided by the onboard Oil Life Monitoring system, but a good rule of thumb is not to exceed 7,500 miles.

Engine Coolant (Antifreeze)

These trucks use a specific Organic Acid Technology (OAT) coolant. It's crucial not to mix coolant types.

• Specification: ACDelco DEX-COOL Coolant (GM P/N 12346290) or equivalent meeting GM 6277M.
• Type: OAT (Organic Acid Technology), Orange color.
• Mixture: 50/50 with distilled water.

Notes: DEX-COOL is a long-life coolant, typically lasting up to 5 years or 150,000 miles, but it's wise to inspect its condition annually. Never mix with conventional green (IAT) or hybrid (HOAT) coolants, as this can cause gelling and severely compromise the cooling system. When topping off, always use a pre-mixed 50/50 DEX-COOL formula or mix it yourself with distilled—not tap—water.

Transmission Fluid

Depending on the engine and build date, the 2018 Yukon came with either a 6-speed or a 10-speed automatic transmission. They use different fluids; using the wrong one will cause damage.

• 6-Speed Automatic (6L80):
  • Specification: DEXRON-VI
  • Capacity (Service Refill): ~6.0 qt (5.7 L)
• 10-Speed Automatic (10L80):
  • Specification: ACDelco DEXRON ULV (Ultra Low Viscosity) - GM P/N 19352619.
  • Capacity (Service Refill): ~7.0 qt (6.6 L)

Notes: This is one of the most critical fluid choices. Never use a "universal" or "multi-vehicle" ATF. DEXRON-VI and DEXRON ULV are not interchangeable. The 10-speed transmission's clutch packs and solenoids are designed for the unique frictional properties of the ULV fluid. Always verify which transmission your specific Yukon has before purchasing fluid. A fluid and filter change is recommended every 45,000 to 60,000 miles for severe service (towing, city driving) or around 90,000 miles for normal service.

Drivetrain Fluids (4WD)

Transfer Case

For all 4WD models, the transfer case requires automatic transmission fluid.

• Specification: DEXRON-VI
• Capacity: 1.6 quarts (1.5 liters)

Notes: The transfer case fluid should be changed approximately every 50,000 miles, especially if the 4WD system is used frequently. It's a simple drain-and-fill procedure.

Front Differential

• Specification: SAE 75W-90 Synthetic Axle Lubricant (GM P/N 19300457)
• Capacity: ~1.7 quarts (1.6 liters)

Notes: A high-quality synthetic gear oil is required. There are no limited-slip additives needed for the front axle.

Rear Differential

• Specification: SAE 75W-90 Synthetic Axle Lubricant (GM P/N 19300457)
• Capacity: ~2.75 quarts (2.6 liters)

Notes: Most 2018 Yukons use an automatic locking rear differential (G80) that does not require a limited-slip friction modifier. Using the standard synthetic 75W-90 gear oil is correct. The fluid should be changed every 50,000 to 75,000 miles.

Brake Fluid

The hydraulic brake system requires a standard DOT 3 fluid.

• Specification: DOT 3 Brake Fluid (GM P/N 19299818)

Notes: Brake fluid is hygroscopic, meaning it absorbs moisture from the air over time. This moisture lowers the boiling point and can cause corrosion in the brake lines and calipers. For this reason, it should be flushed and replaced every 2-3 years, regardless of mileage. While DOT 4 fluid has a higher boiling point and is compatible, it is not required by the manufacturer. Never use DOT 5 (silicone-based) fluid.

Power Steering Fluid

These vehicles use an electric power steering system, so there is no hydraulic power steering fluid to check or change.

Windshield Washer Fluid

• Specification: A good quality, solvent-based washer fluid rated for all seasons.

Notes: Use a fluid that contains solvents to effectively clean bugs and road grime. In winter, use a fluid with a low freezing point to prevent damage to the reservoir and pump.

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