98 STS Oil question

Our 1998 STS runs perfect, no hint of any issue whatsoever with the exception of the check engine light is on and when we bought the car this past spring the fella had a recent print out from the dealer showing an O2 senser was bad, hence the light, the diagnostic showed nothing other than that. BUT... it goes through engine oil. The car does not smoke or leak anything. Can someone clue me in on this? Is there an issue with these engines? I like to use synthetic oil but can't keep dumping it in at this rate.

Also, is it difficult to buy a used key FOB and re-program it for this car?

Thanks!

How much oil is it using? Some of the Northstars have been known to use a bit more oil than others. It is usually from the rings getting carboned up and not sealing correctly. One of the recommended cures it to run the engine hard at full throttle up to 60 MPH or so (at a safe location of course!). If that doesn't work, you can use the GM top end cleaner to try and free up the rings. Very rarely will the rings need to ever be replaced, so most likely they are just stuck.

As for the key fob, the TECH II programmer needs to be used, and pretty much only dealers have that tool!