A lawnmower engine assembly, comprising: an air-cooled lawnmower engine, wherein the air-cooled lawnmower engine comprises: an engine block; an oil gallery configured to distribute oil; a crankcase cover; and a crankcase chamber defined by the engine block and the crankcase cover; and a dry sump lubrication system including: an external oil reservoir having a recommended oil fill capacity of at least 4.73 litres (five quarts), the external oil reservoir comprising: an oil tank defining an oil chamber; and an oil filter assembly comprising: a housing at least partially defining a filter chamber, wherein the filter chamber is in fluid communication with the oil chamber; a filter positioned within the filter chamber; and a vent assembly in fluid communication with the oil chamber, the filter chamber, and the internal combustion engine, wherein the vent assembly is configured to allow air to flow from the filter chamber and the oil chamber to the internal combustion engine; a supply pump in fluid communication with the oil chamber and the oil gallery, wherein the supply pump is configured to draw oil from the oil chamber and provide pressurized oil to the oil gallery; and a return pump in fluid communication with the crankcase chamber and the filter chamber, wherein the return pump is configured to draw oil from the crankcase chamber and provide pressurized oil to the filter chamber; wherein the filter is configured to filter the pressurized oil provided to the filter chamber. an air-cooled lawnmower engine, wherein the air-cooled lawnmower engine comprises: an engine block; an oil gallery configured to distribute oil; a crankcase cover; and a crankcase chamber defined by the engine block and the crankcase cover; and an engine block; an oil gallery configured to distribute oil; a crankcase cover; and a crankcase chamber defined by the engine block and the crankcase cover; and a dry sump lubrication system including: an external oil reservoir having a recommended oil fill capacity of at least 4.73 litres (five quarts), the external oil reservoir comprising: an oil tank defining an oil chamber; and an oil filter assembly comprising: a housing at least partially defining a filter chamber, wherein the filter chamber is in fluid communication with the oil chamber; a filter positioned within the filter chamber; and a vent assembly in fluid communication with the oil chamber, the filter chamber, and the internal combustion engine, wherein the vent assembly is configured to allow air to flow from the filter chamber and the oil chamber to the internal combustion engine; a supply pump in fluid communication with the oil chamber and the oil gallery, wherein the supply pump is configured to draw oil from the oil chamber and provide pressurized oil to the oil gallery; and a return pump in fluid communication with the crankcase chamber and the filter chamber, wherein the return pump is configured to draw oil from the crankcase chamber and provide pressurized oil to the filter chamber; wherein the filter is configured to filter the pressurized oil provided to the filter chamber. an external oil reservoir having a recommended oil fill capacity of at least 4.73 litres (five quarts), the external oil reservoir comprising: an oil tank defining an oil chamber; and an oil filter assembly comprising: a housing at least partially defining a filter chamber, wherein the filter chamber is in fluid communication with the oil chamber; a filter positioned within the filter chamber; and a vent assembly in fluid communication with the oil chamber, the filter chamber, and the internal combustion engine, wherein the vent assembly is configured to allow air to flow from the filter chamber and the oil chamber to the internal combustion engine; an oil tank defining an oil chamber; and an oil filter assembly comprising: a housing at least partially defining a filter chamber, wherein the filter chamber is in fluid communication with the oil chamber; a filter positioned within the filter chamber; and a vent assembly in fluid communication with the oil chamber, the filter chamber, and the internal combustion engine, wherein the vent assembly is configured to allow air to flow from the filter a housing at least partially defining a filter chamber, wherein the filter chamber is in fluid communication with the oil chamber; a filter positioned within the filter chamber; and a vent assembly in fluid communication with the oil chamber, the filter chamber, and the internal combustion engine, wherein the vent assembly is configured to allow air to flow from the filter chamber and the oil chamber to the internal combustion engine; a supply pump in fluid communication with the oil chamber and the oil gallery, wherein the supply pump is configured to draw oil from the oil chamber and provide pressurized oil to the oil gallery; and a return pump in fluid communication with the crankcase chamber and the filter chamber, wherein the return pump is configured to draw oil from the crankcase chamber and provide pressurized oil to the filter chamber; wherein the filter is configured to filter the pressurized oil provided to the filter chamber.