R134a
A 1998 Mercury would use R134a refrigerant.
R-12 unless it has been converted over to R-134a.
Unless it has been converted over to R134 it came with R12. I suggest you convert it to R134a. R12 is very expensive.
R134a
R134a
R134a
Mercon V
5W-30
R134a
R134a
R134a
R134a