Sounds plausible for other uses but when you have real carbon build up there is truly only one way to get rid of it completely, properly, pull the heads. Most opt for a cleaning which involves a tear down and use of a kit we have (out of California) and cleaning and blowing, cleaning and blowing, you should see the crap that comes out of these things, disgusting design, bmw just doesn't care, period! They'll charge you thousands to fix a supposed secondary air flow problem to eventually cave and bring up carbon build up, we see it, trust me, sad.
And no, sea foam is NOT an option.
The biggest concern with the e60's we see isn't the oil leaks or occasional build up we see but rather the huge repair costs associated with the trans, it gets to the point where your higher mileage e60 is barely worth as much as repairing or replacing the trans.
Last edited by Blackedout95; 12-29-2013 at 12:04 PM.