no 100% sure what block i have. 90,000 on the clock 5.3 flex fuel. i use whatever fully synthetic oil autozone is running a special on that week. change it about every 5 to 6 thousand miles. usually she's about a quart low at the 5k mark. its been like that since the first time i changed the oil. i bought the truck new and about 90% of the miles are interstate commute to work miles so it has not been abused.