What could cause a loss of oil in these vehicles?
Oil as a lubricant has a very important function in an internal combustion engine. It is imperative for correct engine operation to have the recommended oil level and viscosity.
Honda vehicles built between 2008 and 2013 evidently have an oil consumption problem with both 4-cylinder and 6-cylinder engines. Honda suggests that burning 1 quart of oil every thousand miles is within the normal range of oil consumption as long as the oil is topped up correctly and the recommended oil change intervals are maintained. If the suggested oil change interval is exceeded, however, the vehicle is on a certain path for excessive oil consumption.
The Variable Cylinder Management (VCM) system in Honda 6-cylinder cars uses oil pressure, vehicle speed and load data to detect vehicle power needs and can shut down some of the cylinders to enhance fuel economy in load ranges when all 6 cylinders are not needed to keep the vehicle in motion. If the oil is low, diluted or contaminated, however, low oil pressure can cause incorrect VCM operation. When the VCM system engages sporadically, it can cause piston rings blow-by, spark plugs fouling and additional oil consumption.
On 4-cylinder vehicles, the oil control rings can stick instead of expanding to the cylinder walls, allowing oil to flow past and burn excessively. Again, this is aggravated by infrequent oil change intervals.
In response to the oil consumption problem Honda launched several service campaigns. For 6-cylinder vehicles, Honda offered a software update to change VCM engagement parameters. If the vehicle continued to burn oil, piston ring replacement was the corrective action.
On the 4-cylinder vehicle, the dealership performed an oil change and the vehicle owner had to return within 1,000 miles to see how much oil was consumed. If there was an abnormal amount of oil consumed, a full engine disassembly followed in order to replace the pistons and piston rings.
Needless to say, Honda USA felt the repercussion of these design flaw at the dealer level. When Honda USA puts out a bulletin of this magnitude they anticipate a flood of customers trying to get the required engine fixes. The free engine and engine management repairs offered by Honda were very similar to safety recalls, reminding me of way people reacted and demanded that their cars be fixed for free.
And now a warning: Regular maintenance can really make a difference in the life span of your vehicle. Lacking regular maintenance, the newly installed pistons and rings can still stick and collapse, sending oil back into the combustion chamber and causing excessive oil consumption.