Dragon Ball Kai - episode 85 - 11 Dec, 2010

As Piccolo completes his training in the Hyperbolic Time Chamber, and Vegeta takes his place, Goku and Gohan are spending their days relaxing at home. Meanwhile, the Self-Defense Army attempt to launch an offensive strike against Cell, but they are completely wiped out. Hearing about this over the radio, Goku asks Piccolo if it is possible to separate with Kami, so he can use the Dragon Balls to revive all the people Cell killed. Since Piccolo can't separate, Goku theorises that he can convince another Namekian to stay on Earth and create a new set of Dragon Balls, and goes to King Kai's planet so he can find the Namekians. (Source: Wikipedia)