Oil consumption only when cold???

[Dr. T]

My BMW consumes oil only during during cold starts. I could drive during 2-3k mi. trips and not consume a drop, but as soon as I do short trips with frequent cold starts, consumption goes way up. Is this an indication of worn valve stem seals? Worn hydraulic lifters or both? Stuck rings?

 

[moribundman]

How about this theory:

Cold oil is thick, which results in better ring seal and higher combustion chamber pressure. However, if the rings are worn, the increased pressure will result in increased blowby and oil consumption.

Yay or nay?

 

[Dr. T]

Good question mori!

Also, on very cold starts, I will also get a cold start knock for stuck hydraulic lifters. Can they be responsible for oil consumption at all?

 

[Steve S]

motor is looser when cold.