Hello Avalanchers, I have 255k +! I have a slight wrist pin slap, according to a couple mechanics. I purchased the 2003 Avalanche 1500 a few years ago and it had 102k miles on it. I did normal services, tune up, filters, and all fluids. Ever since I bought it, I have changed oil every 3,000-3,500 miles. I have been using 20w/50 and add a quart of Lucas, since 200k mikes. This summer, I towed my 22' heavy pontoon boat 5 hours away. Engine and trans was getting hot on some uphill grades, and I was a bit worried, but cooled down as soon as I was on flat highway. I put boat in the lake and on the first rainy day I stopped into a auto repair shop and asked lots of questions. He was one mechanic that said wrist pin is slapping, and not to worry! So back to overheating, he suggested a trans cooler! I said it has one, I have tow package. Guess what, no trans cooler with this tow package!! He installed the trans cooler, and it cooled engine 20 degrees on the hills and much less overheating. trust me the ride home had same hills. Still going strong, and I have been expecting to get a crate motor for 2 years now!
I do all the minor work on my truck, I had a shop put the water pump on last year, and changed the belts.
Hope there is a bunch more 200k + Avalanches out there!