Here is my story:
2014 SHO, 25K Miles
3 weeks ago all of a sudden I get crazy propane smell when I pulled in home from work, and rest of the day I was driving.
I started researching and came up with PTU issue, decided to change oil in PTU, its about that time anyway.
First oil change was smelly business, that smell was all over my garage for week and some how made it inside the house, nasty strong.
Anyway I got 12oz out of PTU, after that change smell mellow out but still come out here and there not as strong.
SO week later I did another change, 14OZ out this time, not as smelly but still had some distinctive smell to it.
After 2nd change, light propane kind of smell once a day maybe.
SO few days after that I was looking for something under the hood and I noticed that the vent tube from PTU was dangling out and not plugged in to PTU, well
I pulled it out to inspect it and found out that top vent filter thing was completely clogged, oil filled the filter material and no air was coming in or out, that made vent hose to come off under pressure and PTU oil was spilling on PTU creating smell.
I removed filter material from that hose, plugged it back on, problem solved...
Hope this helps.