With　the　increasing　number　of　light-duty　passenger　car,　a　large　amount　of　waste　engine　oil　was　produced　yearly　which　has　polluted　the　environment　and　wasted　fossil　resources.　Extend　engine　oil　drain　interval　and　reduce　its　effect　on　engine　emission　is　of　great　importance.　In　this　paper,　a　kind　of　modified-sawdust　engine　oil　filter　was　developed　and　the　study　focus　on　its　effect　on　the　emission　characteristics　and　fuel　consumption　rate　of　spark　ignite　gasoline　engine.　This　modified-sawdust　engine　oil　filter　was　also　compared　with　common　oil　filter.　The　tests　were　performed　in　four-cylinder　direct　injection　gasoline　engine　at　six　different　typical　operating　conditions.　Various　tests　were　proceed　including　the　exhaust　emissions　measurement　of　nitrogen　oxides　(NOx),　carbon　monoxide　(CO)　and　hydrocarbons　(HC)　as　well　as　the　fuel　consumption　rate　measurement.　The　effect　of　engine　oil　change　on　engine　emission　and　fuel　consumption　rate　were　also　studied.　Impurity　element　content　of　waste　oil　and　kinetic　viscosity　were　measured　before　and　after　modified　oil　filter　was　used.　The　results　show　that　relative　to　common　oil　filter,　the　modified-sawdust　oil　filter　has　0.4–2.1%,　3.7–7.5%,　1.6–13.3%　decrease　for　CO,　HC,　NOx　emissions,　respectively.　In　addition,　it　significantly　reduces　oil　consumption,　and　the　three　major　emission　species　(CO,　HC　and　NOx)　was　also　reduced　when　fresh　engine　oil　was　adopted.　These　results　indicate　that　the　use　of　modified-sawdust　oil　filter　is　an　effective　choice　to　improve　gasoline　engine　emission　and　fuel　economy.　©　2018　Energy　Institute