Open interest is the number of contracts held by traders in active positions — they're not closed or expired. For Crude Oil Futures this number is 13.21 K. You can use it to track a prevailing market trend and adjust your own strategy: declining open interest for Crude Oil Futures shows that traders are closing their positions, which means a weakening trend.
Buying or selling futures contracts depends on many factors: season, underlying commodity, your own trading strategy. So mostly it's up to you, but if you look for some certain calculations to take into account, you can study technical analysis for Crude Oil Futures. Today its technical rating is sell, but remember that market conditions change all the time, so it's always crucial to do your own research. See more of Crude Oil Futures technicals for a more comprehensive analysis.