The brass color shavings would lead me to believe that you are looking a pieces of the bearing/bushing that the piston pins go through. I believe that this would be the only area of the engine assembly that has brass bushing bearings, unless there are some brass wear parts in the VCT system that could be failing. I believe that the main and rod bearings are silver in color, but I could be mistaken. You should do a compression test on each cylinder to determine if you have a loss in any one of the 6. I guess the turbos may have something that could be failing that is brass in color too. If the brass is coming from your rods, that probably means that there is piston movement of some sort and that will usually be catastrophic. About 2 weeks ago I brought my 2013 SHO to the dealership to have a vib checked and also have the oil changed. When I walked in the back the first thing I noticed what that the tech was putting 5w-20 full synthetic when the 2013's call for 5w-30. You did say that the last person to change the oil was your dealer, so you may want to go look at your invoice to see what oil type was actually used. If you don't trust the invoice, you can have the oil checked to see what viscosity it actually is. But, if the engine is under warranty, blow it up and let them change it. You are probably better off letting it grenade because then they will have to change the entire short or long block vs. changing only the failed parts.
