Just changed my oil this weekend on my Z66; while not the 8.1, I just wanted to point out to everyone that this is a smaller filter than what was on my 99 Tahoe, thus the filter wrench I have is too big, and I think Hercules screwed the damn thing on.

Figured this out after I had drained all the oil. Thank goodness I hadn't blocked my wife's car in! Took her car to Walmart at 11 PM on Friday night to get the proper wrench.
Yes, I change my oil later in the evening on weekends because it is cooler in South Louisiana at night than during the day; my wife doesn't gripe about what I'm doing; and my 3 1/2 year old is out cold and out of the way.