"Date: Thursday, June 1, 2006 08:10 PM From: J. Johnson <imfatdad@xxxxxxxxx> I was wondering, using a vintage AC unit, will one need to use the older, more costly Freon in order for it to function?? Have been told that the alledged compatible mix stuff out now basically can cause seizures of internals as the oils when mixed together are not truly compatible.. Now if a unit is completely uncharged, the newer 134 (I think is called) CAN be used, yes??? Thanks in advance.." This can be confusing! There are two main types of oil, Ester and PAG. Ester should only be used with R-134a, PAG is a synthetic that works with most refrigerants and is compatible with R-134a or R-12. If you run an incompatible oil the compressor could seize due to lack of lubrication. It's easy when starting with a fresh system -- get the right oil. All new aftermarket systems use R-134a, so you should have no problems. When converting a system make sure all the oil is out then install the correct oil. The oil cans are labeled "not compatible with xxx". Read the fine print! There are a few good conversion sites on the net, a search will turn them up. _______________________________________________ AMC-List mailing list AMC-List@xxxxxxxxxxxx http://www.amc-list.com/mailman/listinfo/amc-list or go to http://www.amc-list.com