This thread reminded me that you guys doing uoa's will really need to keep an eye on fuel and flashpoint. As I mentioned in the other thread, BS does not actually test for fuel dilution but they extrapolate the number from the flashpoint reading.
http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Number=968027
Interesting to see that Blackstone is recommending that the above interval be extended when the flashpoint has dropped to 375. Short trips will increase fuel, as will not taking the uoa sample on a hot engine or a couple of WOT runs before the sample.
I would still be a bit cautious about following Blackstone's advice. I've pointed out errors in their uoa's before. Two cases were uoa's of Rotella T6 that came back with weaker zinc and phosphorus levels than a typical GF-5 5W-30, which is not possible.
-Dennis