Re Hotshot ...

Probably ought to read this site carefully first...

http://www.aircondition.com/wwwboard/current/20418.html

http://hvac-talk.com/vbb/showthread.php?threadid=106042

http://www.epa.gov/ozone/snap/refrigerants/lists/mvacs.html

It is a blend..... and the fact that the EPA allows it does not say that it does things like carry oil around the system well... just that it does not violate their chemistry requirements...

But the biggest problem with any blend .... finding a shop that will work on your system....