GM Repair Questions? Ask a Mechanic for Answers ASAP
This PI was superseded to remove all passenger cars equipped with the LS4. Please discard PIP4492Y.
The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.
On rare occasions, some customers may complain of excessive oil consumption and/or blue exhaust smoke.
Upon inspection, excessive oil will be found in the intake manifold and/or PCV vacuum tube if this PI applies.
If excessive oil consumption (greater than 1 quart of oil every 2,000 miles / 3,000 km) is verified but SI diagnosis does not isolate the cause of it, inspect the PCV vacuum pipe to see if obvious oil drips out of it and/or look through the throttle body opening to see if there is excessive standing oil in the bottom of the intake manifold (as much as a ¼ quart in many cases - a teaspoon or two is typically just normal oil residue).
If excessive oil is present, replace the driver side valve cover with the updated valve cover described below and perform another oil consumption test. These valve covers contain an updated baffle to prevent oil ingestion through the PCV system that can occur if there is an over-aggressive lifter(s).
2008 and earlier vehicles: Replace the driver side valve cover using the part number that is listed in the parts catalog. As of 6/2011, all old GM CCA/SPO stock should be purged of the 1st design valve cover so all remaining stock should be 2nd design valve covers as shown in the photo below. As a result, it is suggested to order this valve cover from GM CCA/SPO rather than a local supplier or another dealer who may only stock the 1st design valve cover. Before installing the valve cover, ensure that the PCV baffle looks similar to the 2nd design valve cover below.
2009-2011 vehicles: Replace the driver side valve cover with part number 12642655.
At this time, the latest version of 10-06-01-008 also lists this updated valve for the 2009 Full Size Trucks and 2009 Pontiac G8 with Engine RPO Codes LC9, LH6, L76, L92, or LFA but it does not include all of the additional engine RPOs and Model Years described above. This bulletin is currently under review and may be updated in the future to include additional engine RPOs and Model Years.
If blue exhaust smoke is present, also drain/clean the oil out of the intake manifold and install the intake with new intake gaskets before releasing the vehicle to the customer. If this is not performed, the customer may return with an exhaust smoke complaint due to the residual oil in the intake manifold even though their oil consumption complaint has been repaired.
There is also this:
Some customers may comment about engine oil consumption on vehicles with higher mileage (approximately 48,000 to 64,000 km / 30,000 to 40,000 mi).
If this complaint is encountered, perform an oil consumption test by following the latest version of 01- 06-01-011.
If the oil consumption rate is greater than 1 quart of oil every 2,000 miles (3,000 km), perform the steps below as necessary:
Inspect the induction system to ensure that it is assembled correctly and that there is no evidence that the engine has been ingesting dirty air due to a miss-assembled induction system.
Follow SI and the latest version of PIP4492 to ensure that the PCV system is functioning properly and that there is no sign of excessive oil in the intake.
If the steps above do not isolate the cause of this concern, this is most likely the result of sticking oil control rings. To correct this condition, perform the piston ring cleaning procedure as outlined in the latest version of 10-06-01-008 and re-evaluate the oil consumption by following the latest version of 01-06-01-011. The AFM pressure relief valve used on the iron block engine opens at a much higher RPM that it does on the aluminum block engine so it is not suggested to install the AFM pressure relief valve shield at this point.
If the oil consumption rate is still greater than 1 quart of oil every 2,000 miles (3,000 km) after performing the repairs above, inspect the intake and exhaust ports/seals for any sign of a valve seal concern. If no valve seal concerns are found, replace all 8 piston and ring set assemblies. Also install the AFM pressure relief valve shield that is listed in the latest version of 10-06-01-008 since the oil pan will be removed to replace the pistons and rings anyhow. Follow the SI Piston and Connecting Rod Assemble Procedure to properly install the new piston rings onto the new pistons. Depending on the engine that you are working on, the replacement rings may have different features than the original rings. Due to the great variation between equipment, machine shops, and technicians performing these repairs, we DO NOT recommend honing or deglazing the cylinder walls though.
This is just because it is generally unnecessary and can induce unnecessary cylinder wall and/or piston ring damage if it is done incorrectly and/or not cleaned thoroughly. The cylinder walls just need to be cleaned thoroughly with brake cleaner before the new piston and ring sets are installed.
You're right, LC9 is mentioned in the first article, but not the second.
It's standard procedure to just change the oil and filter, mark the dipstick, then send you on your way until the low oil light comes on, or until you've gone 1000 miles or so, just some distance so they can measure the actual oil loss. 1 quart in 2000 miles is the basic standard, it sounds like you're beyond that, but it has to be verified.
You aren't the first one to have this problem, if it makes you feel any better. Your dealer will certainly take care of it for you, what ever it ends up being. I feel confident about that.