This guy uses hychill for older cars and r134A for newer cars he knows what he is doing http://icemanmobile.com.au/ he told me that the seals on the newer cars will leak hydrocarbin and the older cars around 2005 or below should be o.k. Did a ring around and finally found out it was true. Info i got was from a local tafe that do the aircon training. They have no reason to to lie basically and they know their stuff.