The oil pump is quite literally the heart of any engine. Responsible for pumping the oil through the entire engine, it is one of the most critical parts, but often one of the most overlooked.

Subaru EJ25 oil pumps should always be inspected before installation on any engine build. Over the years our experience shows that the OEM oil pumps are inconsistently assembled by the manufacturer. It is very common to find incorrectly torqued hardware and, at times, rotor tolerances that are not within specification. IAG now offers a Stage 1 Oil Pump that has the rotor tolerances, hardware, and pressure relief valve inspected. Each pump is also modified to increase oil pressure which aids in ensuring proper oil delivery. The pump is then assembled by our trained staff, providing you with a product which is ready to install, right out of the box.

Each Stage 1 pump starts as a new OEM Subaru oil pump with 11mm rotors. The pump is completely disassembled and checked for contaminants or debris from the manufacturer. The pump is then ultrasonically cleaned.

During the modification process the OEM Pressure Relief Valve Piston is REM polished, providing a low Ra surface, which reduces the friction of the component, and greatly reduces the chance of the piston galling or sticking in the bore - a problem that is frequently seen even on brand new oil pumps.

The piston is reinstalled and confirmed to operate correctly. The rotors are measured and checked to be within the manufacturer's specification - aka Blueprinted, and installed next. The pump is then put together with a light coating of assembly lube to reduce friction and scuffing and aid in priming on first start up.

Finally, the backing plate is installed. Loctite is added to the hardware, and each piece receives a painted mark after it is correctly torqued.

These fit all EJ20 and EJ25 motors, which means 2002-2014 WRX, 2004-2022 STI, 2004-2012 Forester XT, and 2005-2009 Legacy GT/Outback XT.