Coolant leak showing in clear reservoir. Can smell in cabin but dry on ground. Replaced coolant cap and Firestone ran pressure test thinking it was hose issue, the guy's taking preliminary look one day thought there was evidence. No leak found through test, suggested dealer do a more extensive pressure test for engine where they now think problem lies bc even though they can do that test too, they can't fix whatever it will be. Dealer to look Wed. Said worst case $10k engine replacement. 2011 sold to me in Nov described as "mint" condition, so it better not be that. Any thoughts?