Changed out the oil on my Mazda6 yesterday and was literally giddy over the idea of sending in a dino Havoline sample with almost 8,000 miles on it. The bubble burst though when entering the service info into my log, I noticed the last change was in fact 6900 miles prior rather than the 7900 mile interval that I thought I had achieved . Too late now, the pan was drained and filled with the last of my SL/GF3, 5w-20 Havoline and the next fill will mark the beginning of the SM/GF4 era for me. Maybe it's a blessing in disguise in that this is the first time my trusty Havoline dino was stretched well beyond the 5,000 mile mark and I'll get useful info back from Blackstone (and Terry) before going to the full 7500 mile interval. When the report comes back I'll post it up.