Tony:

Synthetic poly-ester type oil used to convert R12 systems to R134a -- dissolves in both the old oil and in the R134a. The oil in an AC system is dissolved in the gas (or liquid) freon. The old petroleum base oils aren't soluble in R134a and cause problems.

A moot point if you AC still works!

Peter

__________________
1972 220D ?? miles
1988 300E 200,012
1987 300D Turbo killed 9/25/07, 275,000 miles
1985 Volvo 740 GLE Turobodiesel 218,000
1972 280 SE 4.5 165, 000 - It runs!