My 2006 X5 M54 engine used to drink 1qt/400-500 miles.

Did the LOWER engine treatment (don't have time to do UPPER treatment with AC Delco thingy). This is what I did:
- 3/4 qt ATF in engine oil for 200-300 miles.
- At oil change, used Lubro Moly Engine Flush, ran engine for 10 min, then replaced oil + oil filter.
- Oil consumption is still the same, i.e., 1qt/400-500 miles

Then I did the poolman, Bavarian CCV mod, 500 miles later zero oil consumption!!!


I am very convinced that my theory above (more crank case vacuum ---> much less oil gets sucked into combustion chamber) is correct.

The key thing is the PCV Valve reducing the flow to appropriate level (3/4-inch ---> 3/8-inch). Some people on youtube didn't use the PCV Valve but they used plumbing adapter to bring it down to 3/8" or so. I still recommend the PCV Valve. Just replace/clean it every 10K-15K or whatever interval you are comfortable with.


This is my setup, thank you all for contributing.



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1998 E39 528i 5sp MT
2006 E53 X5 3.0 6sp MT