Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to 2018 and prior GM passenger cars and gasoline-powered light duty trucks under 8500 LB GVW.

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  Models: 2018 and Prior GM Passenger Cars and Gasoline-Powered Light Duty Trucks Under 8500 LB GVW

Steps to confirm (in the document’s order)

1. Inspect the oil pan and engine covers for leaks from over-tightened, damaged or out of place gaskets, and inspect oil lines and fittings.

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   Inspect the oil pan and engine covers for leakage due to over-tightened, damaged, or out of place gaskets. Inspect oil lines and fittings for signs of leakage.

2. Verify that the dipstick tube is fully seated in the block and that the dipstick is the proper part number for the engine.

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   Verify that the dipstick tube is fully seated in the block. When checking the oil level, make sure the dipstick is wiped clean before taking an oil level reading and fully depress the dipstick until the shoulder bottoms out on the dipstick tube. The dipstick should be the proper part number for the engine/vehicle that is being checked.

3. Let the vehicle sit at least 15 minutes after shutting the engine off before reading the oil level.

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   To assure a sufficient amount of oil has drained back to the crankcase, and an accurate reading can be obtained, 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.

4. Verify that the PCV system operates properly; blockages, restrictions or damage can increase 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.

Repair

• If the final evaluation shows more than 0.946 liter (1 qt) in 3200 km (2000 mi), follow the published symptom diagnostics in the Service Manual.

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  8. If the final evaluation shows that the engine uses more than 0.946 liter (1 qt) in 3200 km (2000 mi), follow the published symptom diagnostics as described in the appropriate Service Manual.

Caution

• The accepted rate of oil consumption is 0.946 liter (1 qt) in 3200 km (2000 mi).

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  The accepted rate of oil consumption for engines used in the vehicles referenced is 0.946 liter (1 qt) in 3200 km (2000 mi).

• This rate does not apply to vehicles driven aggressively, at high RPM, high speeds, or loaded (for trucks); their consumption will be more.

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  Important: This rate does not apply to vehicles that are driven in an aggressive manner, at high RPM, high speeds, or in a loaded condition (for trucks). Oil consumption for vehicles driven under these conditions will be more.

• Vehicles driven aggressively may consume up to 0.946 L (1 quart) every 805 km (500 mi); this is normal and no repair is necessary.

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  Vehicles that are driven aggressively may consume engine oil at a rate of up to 0.946 L (1 quart) every 805 km (500 mi). This is normal for a vehicle that is driven aggressively. No repair is necessary.

• Towing a trailer increases oil consumption.

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  Towing a trailer will increase oil consumption and may cause oil consumption to fall below the normal accepted rate referenced in this bulletin for an unloaded vehicle in a personal use application.

• On vehicles usually driven less than 8 km (5 mi), fuel and condensation can raise the dipstick reading; a later long trip that vaporizes them may look like excessive consumption.

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  On vehicles that are usually driven short distances, less than 8 km (5 mi), especially in colder weather, unburned fuel and condensation generated from cold engine operation may not get hot enough to evaporate out of the oil. When this occurs, the dipstick may indicate that the oil level is over-full. Subsequent driving on a trip of sufficient length to enable normal engine operating temperature for 30 minutes or more, in order to vaporize excess moisture and fuel, may give the customer the impression of excessive oil consumption.

• Do not test oil economy until the vehicle has at least 6400 km (4000 mi), unless the engine is reported to use 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).