Don't be fooled by the noise around falling German bonds or the latest U.S. economic data point. When it comes to trading 30-year Treasuries, what really matters these days is oil.

During the past four months, yields on U.S. Treasury notes have been the most correlated to crude prices in almost two years, according to data compiled by Bloomberg.

Oil has climbed 36 percent from this year's low of $43.46 a barrel on March 17 as energy companies cut production and signs emerged that Europe's stimulus efforts are, in fact, starting to help on the growth front. In that period, yields on long-dated U.S. government bonds have surged to 2.92 percent from 2.61 percent.