Oils formulated for auto A/C systems must have the ability to carry refrigerants as a gas and in a liquid form through a system containing hoses and tubes ranging from 1/16" to 3/4" in diameter, temperatures and pressures from 34 degrees and 34 psi to over 300 degrees and 300psi, and maintain the ability to flow evenly and lubricate a compressor that is turning 5000 RPMs. Two lubricants are miscible with R-134A, PAGs & POEs. PAGs are the lubricant of choice because of their ability to handle moisture better than the POEs. PAGs are enhanced with additives to better lubricate the compressor and protect the metal parts exposed to moisture and acids. PAGs mixed with dyes must be blended to conform to the same stringent formulations. We have sampled PAGs from around the world and have seen products labeled as a PAG 100 which contain 25% PAG/25% Ester and 50% mineral oil. Mineral oil is not miscible with R-134A and will drop out of the formulation. We have also seen products labeled as double end capped PAGs here the blend was a PAG/POE /mineral oil combination. With BVA Auto/AC lubricants you are getting the highest quality lubricants available.