In his 30 years of trading, commodities king Dennis Gartman has seen all types of markets. And now he says he's the most bullish he's ever been on crude oil.

"If you watch the term structure in the futures, you've seen the contango narrow. Crude is no longer aggressively bidding for storage as it was it was six or seven weeks ago," said the Gartman Letter Editor Tuesday on CNBC's "Fast Money." "I think you've seen the lows."

Gartman points out in his daily newsletter that OPEC has increased its production in August, which has caused the WTI/Brent spread to narrow. And if U.S. production continues to fall and OPEC production continues to increase, it is entirely possible to see Brent/WTI narrow to parity. He also pointed to rig counts, which have fallen the last six weeks and, he believes, will continue to fall further.

But it wasn't just oil that has the commodities king intrigued. Since Friday, Gartman says he's become extremely bullish on stocks, gold and grain, each of which he believes have bottomed out.

"I've been bearish of stocks since April, and Friday is the first day I decided to be a buyer," Gartman told producers Tuesday.

He points to Friday's massive reversal as the turning point for becoming bullish.

"I think the world sort of changed on Friday afternoon," said Gartman, when the Dow managed to wipe out a 250-point loss and close 200 points higher for the day.

Gartman says reversal days that large usually mark a changing of the tide in the market. "It means the shorts have thrown up their hands and given in," said Gartman. "The psychology changes."