Beware of general information in regards to O2 sensors when it comes to your Regina. Common knowledge about sensors getting lazy, and needing to be replaced after 60K, etc are based on the common O2 sensors.

Most cars use a "zirconia" sensor which generates voltage based on what's going on in the exhaust stream. Regina, and some Jeeps and Nissans, use a "titania" sensor which changes resistance instead. Titania sensors seem to be much more long lived (maybe because they don't need to be open to the outside air for reference like zirconia). My two Regina cars both have old and likely original sensors at 240 and 205K miles. I bought the $100 spare as Lucid smartly recommends, but haven't put it in yet since I still get 24mpg in the Summer and 21 in the Winter here in Minnesota with 87 octane gas that is 10% ethanol year round.