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Excessive engine oil consumption GM vehicles

Excessive engine oil consumption GM vehicles

GM Service bulletin #10-06-01-008M fix for excessive oil consumption

GM has issued a service bulletin ##10-06-01-008M to address excessive oil consumption on the vehicles listed below. The engines have aluminum or cast iron blocks and are equipped with active fuel management systems (AFM). The fix includes installing an AFM oil deflector and cleaning carbon from the cylinder head. It also includes the installation of an updated valve cover.

Models covered by service bulletin #10-06-01-008M

2007-2014 Cadillac Escalade Models
2007-2013 Chevrolet Avalanche, Silverado
2007-2014 Chevrolet Suburban, Tahoe
2010-2012 Chevrolet Colorado
2010-2015 Chevrolet Camaro
2007-2013 GMC Sierra, Sierra Denali
2007-2014 GMC Yukon Models
2010-2012 GMC Canyon
2008-2009 Pontiac G8 GT

The service bulletin applies to all above vehicles built prior to February 1, 2011 with the following engines:

– Aluminum Block V8 Engine with Active Fuel Management (AFM) (RPOs L9H, L94, LZ1, L99, LC9, LH6, LH9, L76, L92, LFA (Hybrid))

– Iron Block V8 Engine with Active Fuel Management (AFM) (RPOs LMG, LY5)

This bulletin does not apply to the Buick Rainier, Chevrolet TrailBlazer and GMC Envoy equipped with LH6 due to a different design oil pan and AFM pressure relief valve.

Description of the GM excessive oil consumption problem

On higher mileage vehicles(30,000-40,000 miles) you may notice high oil consumption along with a service engine soon light on and a rough running engine. All engines consume some oil, but these vehicles consume more than one quart every 2,000-3,000 miles.

Cause of the excessive oil consumption

GM has determined that the cause of excessive oil consumption is related to two conditions:

1)  PCV pullover—Too much oil is being pulled through the PCV system. PCV pullover or an overactive lifter can cause oil to be pulled through the PCV system even at low vehicle mileage. A correctly functioning PCV system will only leave a film of oil in the intake manifold.

Oil spray that is discharged from the AFM pressure relief valve within the crankcase. If you drive under extended high engine speed operation that oil spray quantity may be more than usual, resulting in excessive carbon deposit formation in the piston ring grooves. That causes increased oil consumption and cracked or fouled spark plugs in cylinders #1 and/or #7.

Fix for excessive oil consumption

For vehicles with aluminum or cast iron blocks built prior to February 1, 2011 and with oil in the intake manifold, install an updated valve cover. If vehicle is built after this breakpoint, it should already be equipped with an updated valve cover (#2 in image below).

old versus new valve cover

Inspect the intake manifold to see if there is any oil puddling in the bottom. If there is you will need to replace the left valve cover.

Two new left rocker arm covers have been released for trucks and vans. Replace the left rocker arm cover with GM P/N 12570427 for 2007-2008 or GM P/N 12642655 for 2009-2011. This rocker arm cover has a relocated PCV drain hole that prevents oil from entering the intake manifold.

Note: These rocker covers are for specific years. The PCV orifice is different for each. The correct cover must be used or an SES light may set.

For Aluminum Blocks where oil is getting past piston rings

To correct this condition, install an AFM shield, perform the piston cleaning procedure as described below and install a new oil pan gasket. Then monitor oil consumption after the repair to ensure oil consumption has improved to acceptable levels.

If this repair does not correct the condition, it may be necessary to replace all of the piston assemblies (piston and rings) with new parts.

Important: It is critical in this cleaning process that the engine/fuel injector cleaner remains in the cylinders for a minimum of 2.5 hours to fully clean the components. The cleaner solution must be removed before a maximum of three hours.

Piston Cleaning Procedure

1. Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).
2. Clean the pistons by pouring 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861803 into each cylinder. Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours. Then remove the cleaner by cranking the engine over with the ignition coils and fuel injector unplugged. Be careful to avoid splling the cleaner on painted surfaces.
3. Remove the oil pan and remove the AFM valve.
4. Install the new shield (1), GM P/N 12639759, and tighten the AFM valve to the oil pan to 20 lb ft.

afm shield

5. Reinstall the spark plugs. Replace the spark plugs if necessary due to full of carbon.
6. Reinstall the oil pan.
7. Re-evaluate the oil consumption.

Important: Some minor scratches may be noticed on the cylinder walls during piston and ring replacement. If the scratch cannot be felt when running your finger nail over it, the scratch is considered normal wear and the block or engine should not be replaced. It is not necessary to hone or deglaze the cylinder walls. Honing may induce unnecessary cylinder wall and /or piston ring damage if it is done incorrectly and/or not cleaned thoroughly. Cylinder walls should cleaned thoroughly with brake cleaner before installation of the new pistons and rings.

Perform piston ring break in

It will take 2000-3000 mi. for the new rings to seat. Adequate break time is necessary prior to rechecking the oil consumption level.

For Cast-Iron Blocks where oil is getting past piston rings – free up piston rings

1. Remove the spark plugs and ensure that none of the pistons are at top dead center (TDC).
2. Clean the pistons by putting 118-147 ml (4-5 oz) of Upper Engine and Fuel Injector Cleaner, GM P/N 88861803.  Allow the material to soak for at least 2.5-3.0 hours, but no more than three hours and then remove the cleaner by cranking the engine with the ignition coils and fuel injectors unplugged,
3. Reinstall the spark plugs. Replace the spark plugs if necessary due to full of carbon.
4. Re-evaluate the oil consumption. If the oil consumption is still greater than 0.946 L (1 qt) in 3,200 km (2000 mi), replacement of the pistons and rings will be required.
Note: It is not necessary to install the shield when doing the piston cleaning on a cast iron block engine since the cast iron block engine uses a different oil pump than an aluminum block engine, which results in a higher engine speed before the AFM pressure relief valve opens (cast iron block engines are less prone to the AFM oil spray condition described earlier). If you find it necessary to replace the pistons and/or remove the oil pan for any other reason, only then should you add the shield.

This service bulletin does not apply to excessive oil consumption on Chevrolet Equinox or GMC Terrain vehicles. To learn more about the lawsuit settlement for that excessive oil consumption problem, see this post.

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