Ford 2.7 here. yes, gotta wait for it before trying the dipstick. I don't think the OC really isn't that bad. THERE IS a fumoto-like product for the 2.7 now. It's a little pricey, but it allows a clean, hose-type connection.
Ford's start-stop has a lot going on behind the scenes - the re-start is fast, it knows which cylinder to fire without getting #1 over TDC, an electronic pump primes the transmission for immediate engagement - just to name a few. If there's a check valve in there, it's because somewhere during product testing, it was needed.