A pimple or dimple on an otherwise uniform oil film on a flat surface decays under the action of surface tension and viscosity. The process is followed analytically from the Navier-Stokes equation, and by optical experiments employing interferometry and the observation of caustics of refraction. Point or line disturbances give a range of recognisable oil hills and ridges, and the theory predicts their shapes and how these scale with time. If the surface is disturbed in a distributed random way, the interferometric contour map shows a random oilscape. The statistics of the oilscape develop self-similarly by changes in lateral and vertical scales which may be predicted and observed. The theory is well verified for the hills, ridges and oilscapes.