The method for the prevention, reduction and/or removal of asphaltene-paraffin-vax precipitates on surfaces in contact with crude oil within oil-wells from bottom hole to well head, in flow lines and pipelines by the use of biocolloid suspensions comprises the steps of: adding together (a) microorganism(s) capable of reacting with, solubilizing of and/or resistant to the components of crude oil, (b) organic or inorganic additives, or (c) a mixture thereof into the pipes; and allowing the so formed suspension containing the microorganisms to act for a desired time. The suspension is used for the decomposition, washing-off and removal of solid hydrocarbons and mixtures of long chain hydrocarbons, as well as for the prevention of formation thereof.