When I had mine done the SA advised that is will NOT cause more damage if left unfixed. Plus considering you have gone 35K miles with the issue on and off I tend to believe this.

Thanks for the info. I guess the best way to do this is when it's winter time I'll bring the car to local dealer and had them give me a full diagnosis. If it's indeed intermediate lever, and if it doesn't hurt the engine(as I understand, when it's too cold the valve will kinda stuck, and the lever that's pulling the valve will not fully open the valve. this caused misfiring and roughness in starting, as well as the SES light), I'll just have to ignore this from now on. If it's something that progresses and cause more damage, I'll either repair the car or sell it/trade it in when it's not too cold.

Was my 2004 E53. The x35d has been great for the first year.

What is the root cause of this issue? Oil condition or mechanical failure after wear?

I think if I remember correctly it was some type of known issue because typically it happened earlier on and people got it covered under warranty. Mine got covered by the aftermarket warranty-thankfully as $5,000 would not be fun.