We consider diagonal cubic surfaces defined by an equation of the form ax + by + cz + dt = 0. Numerically, one can find all rational points of height 6 B for B in the range of up to 10 , thanks to a program due to D. J. Bernstein. On the other hand, there are precise conjectures concerning the constants in the asymptotics of rational points of bounded height due to Manin, Batyrev and the author...