Hi all, have a bit of a conundrum. Any thoughts would be appreciated.

Last Saturday, my 2014 R55 Cooper S sprung the famed coolant leak. I noticed a quick puff of smoke, but everything was still going fine. I continued about a mile down the road, when, after shifting into 3rd gear (car is a manual), I heard a very loud whine. Pushed the clutch, whine went away. Tried 2nd, 4th, and 5th gears (was only going about 35 mph); no noticeable whine. I NEVER noticed this whine before. It happened mere moments after I saw that puff of smoke, and I still had no warning lights on the dash, so I know the car didn't overheat.

I parked the car right after I noticed this and had it towed home, since it was a Saturday evening and nobody was open until Monday.

Monday comes, and I had the car flat-bedded to the dealer. They fix the thermostat, no biggie.

I went back to check on it Tuesday, and went for a ride with the tech, and the gearbox whine is still there.

They kept it, and discovered that the fluid was extremely low. As in, less than 1 cup(!!) of fluid in a trans that should have 3 quarts. They said they didn't see any visible leaks, and refilled the trans. Mind you, only this same dealer and a local MINI/BMW specialty shop have touched this car since I bought it last June as a MINI CPO'd car. Neither has had touched anything on the transmission, just routine maintenance: oil changes, sway bar bushings, spark plugs.

I picked it up yesterday afternoon when they called me. The whine in 3rd is gone, but I still hear it faintly in 6th gear on the highway. Again, it goes away when I depress the clutch.

My question is two-fold:

1) Am I totally screwed? Nobody has touched the trans, and it has no leaks supposedly, but I had next to no fluid for who-knows how long. I'm about to embark on a trip to MOTD, so I really don't want to be stranded on the side of a road somewhere in the boonies.

2) What could have caused the trans fluid to disappear like that, and why did it take so long to manifest? Like I said, nobody has touched that transmission in the 1 year and ~20k miles since I took ownership, and the problem never manifested until the coolant leak showed up.

I'm totally baffled by this. I've seen some other threads where folks have had transmission whine caused by various things, but this seems very unorthodox. The dealer doesn't seem very concerned, and I really don't want to risk a 1500+ mile journey to The Dragon with two friends when the car is not safe to drive. I'm keeping an eye on where the car is parked for any leaks too, so maybe the question will answer itself.

But any thoughts you all may have would be greatly appreciated!