Originally R-12,
May have been and perhaps should be converted to R-134
The oil filter for a 98 Olds Regency is on the side of the engine. The filter is a screw on type.
R134a
R134a
134a
R12
R12
r134a
R134a
R-12
My 2000 uses 134A and looks stock...
R12 unless it's been converted.
It was built to use R12, but can be converted to R134a