I normally check oilprice.com to find out the current trading prices of crude oil. During the week, the updated quotes are typically delayed by ~10 minutes or so. I am looking today, on a Saturday, and the last updated price is from Friday at 5pm. Why is the price delayed so long? Does this have to do with the website simply not giving me the information (because of lack of premium membership or something) or because it doesn't have the information (because of lack of liquidity or something over the weekends)? I can't imagine it's the latter, since I thought commodities trade roughly 24/7 (or is this totally wrong)?
What they're showing you is indeed accurate. Take a look at the contract specification for the CME's WTI Crude Oil Contract and you will see that it trades Sunday through Friday. So if you check on a Saturday, the last price update would be from Friday.
To verify that oilprice.com isn't lagging behind as could be the case for any number of financial data providers, you can compare with other sources such as CME's quotes page which right now (Saturday) also shows a last price from Friday.
As a side note, I would be cautious of price moves that occur during illiquid hours, especially when there are no headlines warranting such moves, or when such moves are out of sync with other global trading venues (e.g. crude trading in Asia/London)