In this study the crystallization behavior of n-paraffins in the waxes has been studied using X-ray diffractometry and photomicrography. The effects of solvents and of a pour-point depressant additive on the lattice properties of the waxes have been investigated and the mechanisms of gel formation and additive action have been studied. In this article we show how to obtain wax diffusivity and solubility values in crude oils from deposition measurements . Providing a rather accurate knowledge of such quantities is of great importance in predicting the wax deposition rate in pipelines. In this work a laboratory simulation of paraffin deposition using a specially designed flow-tube apparatus will be described. This was used to determine the deposition from a crude oil obtained from the wells of a real field. Due to thermodynamic approaches Liquid–solid phase equilibrium measurements were carried out at various pressures and temperatures below the onset of crystallization in a mixture .at the final the mechanism of action of additives that control the sedimentation of paraffin crystals after their crystallization in model diesel oil has been studied.