2011 Silverado Z71 5.3 Bought it in Nov. Didnt know about BITOG then. Found BITOG, immediately dumped the factory fill at 2100 miles, filled with PP 5w-30 ACdelco filter. OLM still reads 21% and the emails from ONstar are estimating a 6600 OCI im dumping mine at 4500 since im a volunteer fire...