My indy says that it is now OK to use PAG oil in old R12 systems and that they(mineral & PAG oil) will mix and work well together. Anyone have an update on this subject? Past threads that I've found really don't deal with this subject directly except to say that O rings might be weakened by the PAG oil. I will be staying with R12.

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Paul 1987 300 SDL; 2000 ML; '69 MGB; '68 VW Fastback

Take a look at the 609 manual here:
http://www.epatest.com/
It addresses that very issue.

You did not say if you are changing to 134 or staying with R12. Either way I would definitely NOT use PAG in the system, but I SURELY wouldn't use it in a system with R12 refrigerant.

R12 is coming down in price and it is the best choice for an original R12 system.

Good luck,