Chemicals are added to crude oil to ensure that it flows from the well to the processing plant. Depending on the composition of the reservoir fluids being extracted (crude oil, reservoir water, natural gas), paraffin may be separated from the crude oil, hydrates may be formed from reservoir water and natural gas, and the combination of reservoir water and crude oil may form an emulsion. Those situations should be avoided to ensure continuous flow from the wellbore to the processing plant. To this end, chemicals, paraffin inhibitors, hydrate inhibitors, and demulsifiers are used. Based on the literature on the subject and on the author’s own experience from observing technological processes, research methods were proposed to assess the effectiveness of chemicals used to ensure the continuity of crude oil flow. The crude oil selected for the tests was characterised by a high content of paraffins, asphaltenes, chloride ions, and water. To determine the onset of paraffin precipitation, tests were conducted based on a change in viscosity and a coupon method – determining the weight gain on a coupon to check the effectiveness of a paraffin inhibitor. The rate of emulsion separation was evaluated in separating funnels. The water released from crude oil often leaches the salt contained within it. Various demulsifiers were used to investigate the separation of emulsions and the purification of oil from salts; silicone demulsifiers in particular were considered. To determine the change in the amount of salt in crude oil, a conductometric measurement was performed. The amount of demulsifier used for phase separation was determined by changing the surface tension. The proposed solution for the use of chemicals to transport and purify crude oil yields tangible economic benefits. The article summarises the research procedures and presents the results for selected crude oil and chemicals.