An apparatus for mixing viscous fluids in a container through applied rotational and oscillation motions is provided. The apparatus has a sample carrier platform mounted to a shaft along a longitudinal axis with a first mechanism imparting oscillating motion to the shaft and a second mechanism imparting rotational motion to the shaft and carrier platform along the axis simultaneously or sequentially. Couplings to the shaft allow the shaft to freely rotate at the same time as it can be pushed or pulled along the longitudinal axis. Sequence, duration and frequency of oscillations and rotations are controlled with a programmable controller.