the present invention relates to a process for producing oligomers and a method for improving the low temperature properties of fatty alkyl esters by using these oligomers . the oligomers according to the present invention are used as pour point depressant and cloud point reducer to improve the pour point and cloud point of fatty alkyl esters such as isopropyl , butyl , ethyl , ethylhexyl esters particularly fatty acid methyl esters at low temperature .