I stick with the Motorcraft filter, and Mobile 1 full synthetic 5w20. My 2010 V10 takes 6 quarts, and that brings it right up to the full dot. I'm one of those that likes to keep the bolt in instead of a valve on the drain pan. Not that big of a deal to change it, and I just don't like the idea of a valve being under the drain pan. From what I've heard it kind of drains slow through that valve as well, but to each their own.
I understand that later V10s required 7 quarts, but if OP isn't getting up to the bottom dot on the dipstick, I wonder if he has an auxiliary oil cooler installed? I think some came from the factory that way.