Three factors might be signaling a selloff in crude oil, R.J. O'Brien Senior Vice President Todd Colvin said Friday.

"I think if you're talking about oil … you have demand down, you have supply up, and you have usage sort of treading water here," he said. "If you look at motor vehicle usage numbers that came out, they stagnated since '07 after rising for close to 50 years constantly. Of course, that's going to mean lower oil prices."

On CNBC's "Halftime Report," Colvin said he was concerned about volatility in West Texas Intermediate crude.

"Not seeing price spikes when we see things that are happening in Europe and the Middle East—that, to me, suggests that the market is a little bit complacent," he said. "And while I do believe that oil is in the middle of a bear market here, it's difficult to stomach these spikes like we saw yesterday down to $90 and change and then right back up to $93.

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"I think that scared a lot of bears out of the market for today and into the weekend, but ultimately I think prices are headed lower."

—By CNBC's Bruno J. Navarro