Manufacturer communication — 2006 GMC YUKON DENALI XL

• Applies to 2016 and earlier GM passenger cars and trucks.

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  Models: 2016 and Prior GM Passenger Cars and Trucks

Possible causes

• Some aftermarket crankcase flushing materials were found incompatible with GM engine components, with potential for damage to some engine seals and bearings.

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  Analysis of some of the aftermarket materials used for crankcase flushing indicate incompatibility with GM engine components and the potential for damage to some engine seals and bearings.

Repair

1. Replace transmission fluid only by draining and refilling, following the Service Information procedures.

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   Transmission fluid should only be replaced by draining and refilling following procedures in Service Information (SI).

2. For the transmission oil cooler, the flow check and flush with tool J-45096 is the approved procedure (Transmission Fluid Cooler Flow Check and Flush).

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   Refer to Transmission Fluid Cooler Flow Check and Flush in the Service Information website using the J-45096.

Caution

• GM does not endorse or recommend engine crankcase flushing for any of its gasoline engines.

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  does not endorse or recommend engine crankcase flushing for any of its gasoline engines.

• Flushing of A/C lines, radiators, transmission coolers and power steering systems is a recognized practice only after catastrophic failures or extreme corrosion found in radiators.

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  Flushing of air conditioning (A/C) lines, radiators, transmission coolers, and power steering systems are recognized practices to be performed after catastrophic failures or extreme corrosion when encountered in radiators.

• External transmission fluid exchange or flush machines are not recommended for automatic or manual transmissions; they may affect the operation or durability of the transmission.

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  The use of external transmission fluid exchange or flush machines is not recommended for the automatic or manual transmission. Use of external machines to replace the fluid may affect the operation or durability of the transmission.