My 02' LS and my 06 LT had that same junk in the overflow. Replaced the coolant and cleaned the tank and all good. For low coolant check your water pump. Don't know if there the same but mine when out at 59K.

 

Hi i have an 06 SS and just got it a month ago. Just had the check tire pressure system light come on and also noticed a noise when turning the wheel at very slow speeds or when stopped. has anyone else had these problems?

 

I call it Dex Crap and I flushed both Montes out and put the reg coolant and no sludge for me!

 

There is a recall for the TPMS. You have any warranty left? If so, take it in.