Our leased 2007 Chevrolet Equinox includes a Tire Pressure Monitoring System (TPMS) with aluminum tire valve stems made in China via Dill. 3 have oxidized and crumbled in the past year. The CSR I spoke with at GM (Deloris x2677) never heard of this defect. However, the Ministry of Transportation has had "numerous complaints" and are investigating. In the meantime, we have to drive our Equinox with little time-bombs on our tired. Any Grade 8 metal shop student knows that untreated aluminum oxidizes and becomes BRITTLE! Why... read full review »