Marshall,

I had a R-134a conversion done on my BMW 528e two years ago by a top-notch
A/C shop in the Atlanta area.  The shop owner said that after a system
purge the old oil remaining in the compressor just sits at the bottom and
does not interfere with the R-134a or the new ester-based oil.

So far no problems other than reduced cooling efficiency.  I recommend
putting a label in engine compartment stating conversison and oil type.

Bill
83.5 Westy with A/C to be fixed sometime in the future.

>
>Question: (Background) When I get the refrig techs to pull the r12 out,
>much of that old mineral oil will remain in the system, primarily in the
>compressor. The thing is, these kits are designed to work with a "small"
>residual amount of
>mineral oil.
>
>So, how to get rid of the oil?
>
>My best guess:
>
>1. get techs to remove r-12;
>2. Find a drain plug on compressor, remove and drain oil (such a thing
>exists? - Bentley says compressor holds 5 oz of oil!) then reinsert plug;
>3. Get techs to restore vacuum again in system;
>4. Charge system according to package directions.
>
>What do you think? Is there a drain plug on the compressor to use for
>draining old oil?
>
>
>BTW:
>
><Yankees will find Canada a VERY cheap to visit. We had dinner at Perkin's
>last night in Grand Forks, and the menu prices were about the SAME as
>Winnipeg's.>
>
>
>Marshall Ruskin
>84 Westy "Iron Igloo"
>Founding Member of "Vanagon's Anonymous"
>