i have a 1985 OLDS CUTLASS SALON WITH 40,000 MILES ON IT

GM Media Archives has a wealth of information about GMs made over the years. Visit their website. You might also be able to get a copy of the original factory to Dealer invoice for your Oldsmobile, if 1985 is available. Buying a carfax may tell you when and where it was first delivered. Vehicles from 1981 and newer can be carfaxed but information before 1994 is spotty. For example the carfax report for my 93 Chevy Caprice shows where and when I bought it (October 16, 1993) but then nothing until January of 2000. My local Chevrolet Dealer didn't start reporting to carfax until January of 2000, that's why. Hope that helps! Jim