an oil filter assembly has an outer canister in which full flow and bypass flow filtration sections are operatively housed in a nested relationship . oil forced into the canister has imparted thereto a vortex flow pattern which forces contaminant particles in the oil away from the full flow filter section before the oil passes therethrough . the bypass filtration section is disposed within the full flow filtration section and creates a second vortex flow pattern in the oil which induces a small portion thereof to flow through a bypass filter element while at the same time causing the entire balance of the oil to bypass this filter element and be discharged from the canister after having traversed the filtering portion of only the full flow filtration portion of the filter assembly .