Andy, The issue is NOT grade or quality of oil as you describe.. The R12 and R134a oils are NOT COMPATIBLE. Mixing them will clog the system and cause compressor failure. Marc > -----Original Message----- > From: Soma576@xxxx [mailto:Soma576@xxxx] > Sent: Friday, April 26, 2002 5:05 PM > To: dmcnews@xxxxxxxxxxxxxxx > Subject: Re: [DML] A/C conversion > > > Marc, > > for refrigerent oil we opted to use Ester 100 which covers a broader > viscosity range than standard "R-12 oil". It isn't as > perfect a match as > purely 134a oil, but it will be adequate for the temperature > and climate that > my DeLorean is in.