An innovative magnetic filter in combination with a Mandhala magnet for oil filtration processes has been developed. With this filter design also nonmagnetizable particles can be separated. Responsible are hetero agglomeration processes that arise due to agglomeration of magnetizable with nonmagnetizable particles. Separation efficiencies in dependence of the particle size distribution and particle shape are quantitatively determined. An evaluation method for the quantification of the separation efficiency of nonmagnetizable particles is developed and validated by experimental data. On this basis, a statement about the efficiency of the hetero agglomeration can finally be made.