Manufacturer communication — 2006 GMC YUKON XL 1500

• Applies to 2000–2019 GMC Sierra, 2500/3500 and Yukon XL, among other listed GM trucks and vans, with a gasoline engine and rated at 8600 GVW and above (note: the Yukon XL range runs to 2019).

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  2000–2019 GMC Sierra, 2500/3500, Yukon XL 2000–2022 GMC Savana 2003–2010 GMC TopKick C4500-C5500 Series Models 2003–2010 HUMMER H2 with Gasoline Engine and Rated at 8600 GVW and above

Possible causes

• Oil usage is directly related to the amount of fuel used: the harder an engine works, the more fuel and oil it uses.

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  Oil usage has a direct relationship with the amount of fuel used. The harder an engine works, the more fuel and oil it will use.

• Towing a trailer or hauling additional weight will increase oil consumption.

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  Towing a trailer or hauling additional weight will increase oil consumption.

• Piston scuffing, excessive piston-to-wall clearance, tapered or out of round cylinders, and worn, damaged or improperly installed valve guides, seals and piston rings all increase oil consumption.

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  Piston scuffing, excessive piston-to-wall clearance, tapered or out of round cylinders, worn, damaged or improperly installed valve guides, seals and piston rings will all cause an increase in oil consumption.

Steps to confirm (in the document’s order)

1. The accepted rate of oil consumption for gasoline engines in vehicles at or above 8600 GVW is 0.946 liter (1 qt) within 379 liters (100 gallons) of fuel used.

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   The accepted rate of oil consumption for gasoline engines in vehicles at or above 8600 GVW is 0.946 liter (1 qt) within 379 liters (100 gallons) of fuel used.

2. Inspect the oil pans, engine covers and the engine oil cooler for leakage, and inspect for oil leakage into the engine coolant.

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   Inspect the oil pans, engine covers, and the engine oil cooler for leakage. Inspect for oil leakage into the engine coolant.

3. Let the vehicle sit for at least 15 minutes after the engine has been shut off before reading the oil level, so the oil has time to drain back into the crankcase.

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   The vehicle should be allowed to sit for at least 15 minutes, after the engine has been shut off, before taking an oil level reading to assure the oil has had enough time to drain back into the crankcase.

4. Verify that the positive crankcase ventilation (PCV) system is operating properly; blockages, restrictions or damage to the PCV system can result in increased oil use.

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   Verify that the positive crankcase ventilation (PCV) system is operating properly. Blockages, restrictions, or damage to the PCV system can result in increased oil use.

5. Begin the oil consumption test after the next regularly scheduled oil and filter change; oil changes should not be performed during the test.

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   Begin oil consumption test after next regularly scheduled oil and filter change. Oil changes should not be performed during the test.

6. The customer records date, odometer, oil level, fuel added and engine hours at each fueling, and returns when the oil level is at or below the add mark, 0.946 liter (1 qt) low, or after at least 4800 km (3000 mi) since the test began.

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   Ask the customer to verify and record the date, odometer, oil level, fuel added, and engine hours, each time the vehicle is fueled, following steps 3-5 and return the vehicle to the dealership if the oil level is found at or below the add mark, 0.946 liter (1 qt) low, if possible. The dealer will add oil to return the oil level to full. If the oil level remains above the add mark, the customer should continue to operate the vehicle and verify the engine oil level until either the oil level drops to or below the add mark or at least 4800 km (3000 mi) has accumulated since the test began before returning to the dealership for a final evaluation.

Repair

• If the final evaluation shows the engine uses more than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, follow the published symptom diagnostics in the appropriate Service Manual.

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  If the final evaluation shows that the engine uses more than 0.946 liter (1 qt) in 379 liters (100 gallons) of fuel used, follow the published symptom diagnostics as described in the appropriate Service Manual.

Caution

• Part of the oil film left on the cylinder wall is consumed during combustion, so varying rates of oil consumption are accepted as normal in all engines.

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  During the combustion process, part of this oil layer is consumed. As a result, varying rates of oil consumption are accepted as normal in all engines.

• Oil economy should not be tested until the vehicle has accumulated at least 8000 km (5000 mi) and the oil has been changed for the first time.

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  Therefore, oil economy should not be tested until the vehicle has accumulated at least 8000 km (5000 mi) and the oil has been changed for the first time.