Manufacturer communication — 2006 GMC YUKON DENALI XL

• The model list includes the 2000–2019 Yukon XL, among other 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 Yukon XL 2000–2025 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

• 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.

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 stated as 1 liter (1 qt) within 400 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 1 liter (1 qt) within 400 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. 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.

4. Wait at least 15 minutes after the engine is shut off before checking the oil level, so most of the oil has drained back into the crankcase.

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   Wait at least 15 minutes, after the engine is shut off, before checking the oil level to make sure that most of the oil has had time to drain back into the crankcase.

5. Check the oil level and record the vehicle mileage, date and exact oil level on the bulletin's form, then make sure the oil level is at, but not above, the full mark on the dipstick, adding oil if necessary.

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   Check the oil level and record the vehicle mileage, date, and exact oil level on the form included in this bulletin. Next ensure the oil level is at, but not above, the full mark on the dipstick. add oil if necessary.

6. Ask the customer to schedule an appointment and return to the dealer for inspection once they have consumed 100 gallons (= 378.5 L) of fuel.

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   Ask the customer once they have consumed 100 gallons of fuel schedule an appointment and return to the dealer for inspection.

Repair

1. 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.

2. The labor operation for the oil consumption test is 0600334, 0.5 hr.

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   0600334* Oil Consumption Test 0.5 hr

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.

• This rate applies only to vehicles under warranty, maintained per the appropriate maintenance schedule, driven at legal speeds and within the design intent of the vehicle.

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  This rate only applies to vehicles under warranty, maintained in accordance with the appropriate maintenance schedule, driven at legal speeds and within design intent of the vehicle.

• Oil economy should not be tested until the vehicle has accumulated at least 6400 km (4000 mi), except when an engine is reported to be using more than 0.946 liter (1 qt) in 1600 km (1000 mi).

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  Therefore, oil economy should not be tested until the vehicle has accumulated at least 6400 km (4000 mi). An exception would be allowed only if an engine is reported to be using more than 0.946 liter (1 qt) in 1600 km (1000 mi).