Hello all, I bought my wife a 2011 Traverse and have been in a constant battle with the way the interior smells. The smell happens when the vehicle has the a/c set on "fresh" air and either at low speeds or at a stop. I have found some other posts relating to this but I am wondering if anyone has found a permanent fix. It is a 2011 AWD, and I genuinely like the car but the smell is horrible. It has been to the dealership on three different occasions. Prior to 08-30-2012, they installed a charcoal filter system (#10-01-37-002 dated 12-09-2010), and they advised that this should remedy the problem. Unfortunately it did not. I picked up the vehicle from the dealer on 08-29-2012 and they advised me that the charcoal filter was completely clogged and they cleaned it. This never seemed to work in the first place. The stated cause in the TSB is "The condition may be caused by PTU (transfer case) fluid odor being pulled into the vehicle through the HVAC air inlet due to the location of the PTU vent". I guess my questions are: Is there a fix for this that GM will approve (apparently there is a vent tube fix, but GM wont approve this)? Is there a long term problem with breathing this? I am getting close to being at my wits end. They advised me that they could replace the oil with synthetic, but it would be at my cost, and it would still be unknown if this would fix the problem. I have the print out of the filter installation procedure, if anyone is interested I can try to scan it and post it.