Investigation of Oil Consumption Issues should begin with the CCV / Intake system. Oil in the intake should not be considered normal and reduced to as minimal amount as possible. Oil that is sucked thru the intake will cause carbon build up on the intake/exhaust valves and the pistons. This will also contribute to catalytic failure and have an effect on engine performance.
My car: 2006 BMW 550I V8 N62TU - 94,500 miles
(No external leaks)
After I replaced the CCVs, It smoked and would not pass Smog Inspection. These issues were fixed with a carbon cleaning chemical regiment (Sea Foam). But it continued to use a quart + of oil every 2>3 tanks of fuel. (Everyone had previously said that this was normal for a BMW) After my modification to the crankcase vent system - It may have used - maybe (it's hard to tell) less then a pint after 2>3 tanks full of fuel.
My Fix: (about 1 hour)
1 - Scotch Brite (3M) pad #7447
2- Stainless steel garden hose screens
(mine had o-ring attached)
- Cut 4 pieces of Scotch pad approx. 1.75 X 1.75 inches.
- Trim rubber washer attached to the hose screen so it fits snug within the valve cover vent tube.
- With CCV diaphragms removed, fold over 1 piece of pad and insert within the slot of the inlet vent port. Be sure pad is pushed low enough so it will not interfere with the diaphragm when reinstalled, but firm enough to stay in place. Reassemble and repeat on opposite valve cover. This is a pre-filter to prevent oil from CCV.
- With vent tube removed (valve covers to intake), fold over 1 piece of pad and insert within valve cover vent outlet nipple. (It may be necessary to trim some length of pad for vent tube reinstallation) Insert screen above pad - this keeps pad from being sucked into the intake manifold. Repeat on opposite valve over and carefully snap vent tube in place. This is a after CCV filter to stop any oil that may have made it past the pre-filter.
- Top off engine oil and keep track of progress.
- I will continue a carbon cleaning regiment at least every 10,000 miles.
Note; This Scotch Brite pad #7447 is about 1/4 in. thick - a thicker pad can be used as available - just compensate for this change.