Billionaire-buddies Warren Buffett and Bill Gates went on an 'Excellent Adventure' Monday. Buffett tells me he and Gates, his good pal and Berkshire Hathaway (BRK) boardmember, hopped a plane to head north to an oilsands development in Alberta,Canada near Fort McMurray. Buffett told me he took the trip to "just look around and learn a little" about the process by which oil is extracted from rocks. The company that runs the massive multi-billion dollar project is Canadian Natural Resources (CNQ), whose stock ended up 7% today on the mere whiff Buffett visited the project.NO investment has been made by himat this point. Now, I should tell you that at past Berkshire Hathaway shareholder meetings I've attended, he and his longtime cohort Charlie Munger have been asked about whether they'd be interested in investing in oilsands. "We don't understand it yet" was the response. Clearly, though, Buffett's interest is piqued enoughso that he at least wanted an "Oilsands 101" quickie class by going up there to visit. But don't think Bill Gates is simply along for the ride. In fact, Buffett told Fox Business in May that it was *Gates* whobeathim to the railroad punch by investing in Canadian National Railway (CNI) before Buffett finally dove in much later by picking up large stakes in Burlington Northern (BNI) and Union Pacific (UNP). But there's a lesson to be learned from Buffett's investment style: he won't commit a single dollar to any company until he fully understandsthe business and believes it fits into his tried and true investment parameters. Now, sometimes he'll buy an entire business outright without ever seeing it if he just gets the sense it's exactly what he wants. He did that with an Israeli auto parts maker, ISCAR....a business hetold me is"the best he's eversee, run by the smartest people ever." He's been known to read an annual report and then commit hundreds of millions of dollars to the stock.... witness Petrochina, an investment that made him and his shareholders billions. But if it's publicly-traded, he scrutinizes annual reports and delves deeply into the bones of a company before he'll put his shareholders' (or 'partners' as he calls them) money to work. He and Charlie admit their style is'boring' and 'simple' but clearly it works. Buffett is the world's richest man, and Gates isn't far behind.