Man, kinda sensitive to unfriendly commentary?  I'll try to spare your
feelings.:)
I have heard the ester oil in the conversion kits protects the compressor
seals.  Apparently R12 helps cool and lubricate the compressor better then
134A, so R12 systems can get by with a "lesser" oil.  This is purely
opinion, from people I have talked to.
The ester oil is more expensive, but not that much, like 8 dollars a bottle.
Seems like the smart thing to do would be just buy a bottle and pour it in.

-----Original Message-----
From: Mark B. Magee <condor2@FLASH.NET>
To: Vanagon@VANAGON.COM <Vanagon@VANAGON.COM>
Date: Wednesday, May 20, 1998 9:23 AM
Subject: Vanagon A/C: R-12 to R-134a No-Mod Changeout

>Volks,
>It's getting hot and smoky down here in the South. I have to leaky
>Vanagon A/C's, I am hearing much talk of successful changeovers from
>r-12 to r-134a by doing nothing except evacuating the r-12 and putting
>in the r-134a. All blows cold and no problems.
>Now before anyone flames me that this is not what the book calls for, if
>you go and purchase a r-12 to r-134a kit from VW for Vanagons after 85,
>they tell you to only change out:
>the compressor oil to ester,
>the accumulator (for system was opened up)
>new 0-rings on accumulator.
>evacutate
>install r-13a
>
>Therefore the old mineral oil left in circulation must not be a big
>issue. So what's wrong with the mineral oil in the compressor????
>This is experimental for sure, but apparently this is being done daily,
>that is the direct changeouts r-12 to r-134a with -no- modifications and
>all is working fine.
>Anyone done this, I will do it on my 91 Westy irrespective due to being
>out of refrigerant, and I must find the leak with the r-134a.
>All feedback appreciated, throttle back any afterburners however.
>
>><>     ><>     ><>     ><>     ><>     ><>     ><>     ><>     ><>
>Shalom
>Mark B. Magee
>82 Diesel Westy
>87GL
>91 Westy
>96 Suzuki 4WD Sport
>Kemah TX USA
>John 14:6