USO is an oil futures ETF that involves rolling futures, earning a red light risk score due to associated costs, and historically, oil price gains have not translated to ETF returns. Rolling futures introduces contango and other costs that erode returns over time, making USO an inefficient way to gain long-term oil exposure. AVOID USO for long-term investment in oil due to structural inefficiencies and high risk, despite its appearance as a vanilla ETF. Short-term trades during specific market conditions might benefit, but it is not designed for buy-and-hold strategies.