As the US and Israel's attack of Iran has reminded the world, oil remains as integral as ever to the global economy. But the ETFs for investing in crude come with some caveats—and are a big reason why Bloomberg Intelligence introduced its traffic-light system.

On this episode of Trillions, Eric Balchunas and Joel Weber speak with Bloomberg Intelligence's James Seyffart, an ETF analyst, and Vincent Piazza, a senior energy analyst. They discuss Piazza's "delay, disruption and destruction" outlook; how the United States Oil Fund (USO) came back from the dead; and what to know about other noteworthy energy ETFs such as XLE, CRAK and even BWET.