Came across this today and thought I'd share. It's a coupon for $10 off of any Mobil 1 oil if you buy at least 5 quarts, or one of the 5 quart jugs. You also have to buy it at Autozone.
http://www.mobiloil.com/USA-English/MotorOil/Files/Mobil_1_$10_off_Coupon_at_Autozone.pdf
You might need to copy and paste the link. It's not working correctly when I click on it from here. I think the dollar sign is messing up the tag.
I think I'm going to use this to try out the 10W-40 4T oil in my C-14. I have less than 1500 miles on the Rotella 5W-40 Synthetic and my shifting already feels pretty notchy.