2006 Cayenne oil consumption

[poorsche]

Has anybody here resolved the engine oil consumption issue by replacing the driver's side valve cover assembly? It houses the crankcase vent valve which is not sold separately. The car is a twin turbo with about 60K miles on it.

Edited February 7, 2012 by poorsche

[clarksongli]

The oil consumption issue is not oil leaking out of the motor. Although if you have a leak it would be good to fix that.

There are two main contributors to the oil consumptions:

1. Turbo motors......because they relay on a fluidized bearing for the wheel shaft.....naturally the sealing ability will break down over time. Considering the temperature cycling and speed of the turbine wheels.....it is expected to start seeing some oil movement with mileage. Generally, the majority of it will be burned off, and you may not notice....but obviously the older you get the worse it will be(eventually too much shaft play will force a turbo rebuild/replacement).

2. 4.8L V8s.........the main consumption in a motor is due to the rings and the sealing surface area. If we look at our motors, we have roughly 85" or ring area to seal. if you compare that to a Honda 4cylinder, they only have about 30". Now you can make a linear assumption of oil consumption, but because rings are not 100% sealing, especially over time.....you have more area to seal against combustion/oil.

With that being said, i generally burn about 2 quarts every 6-7k. Considering this motor is over 2.5X the size of most 4cylinders.....law of probability says we will generally burn more oil....which is perfectly normal.

Now if you burn a quart every day, there might be something bigger going on. Another point of leakage are the valve stem seals.....unless something mechanically went wrong with your valvetrain, there isn't generally a reason to assume a stem leak though.....only time i have seen an issue is a physical chunk of metal went through the valve or a bent valve which ovalized the guide and seal.

The last thing i will leave you with is the VAC system on the cayenne.....we pull vacuum on all of the oiling points to remove vapors and so forth.....the vacuum is pulled by the intake side(low pressure) of the driveside turbo. Over time, that oil vapor builds up and will create some standing oil in the piping.....again not enough to cause noted oil loss....but something to be aware of.