Yesterday I did my spark plugs, pcv valve, oil change, front and rear diffs and transfer case. Both the diffs were black and my plugs were nearly there. I have a 06 v6 sport with 110k and I'm pretty sure the fluids were never changed. I bought it a couple weeks ago and drove it about 800 miles to get back home, best I could get mpg wise was 16.2 on the computer. It was off by about 2 miles, when I filled up I divided miles to gallons and I was only getting about 14.5 mpg. Well driving home today my computer was reading about 21 mpg so hopefully I'm getting around 17-18mpg. Quick tuneup can yield 3 more mpg, hell yeah!