Stage X Baffled Sump & Catch Tank Kit 2006+ Twin Scroll

Oil control is a particular problem for the Subaru flat-four boxer engine because of its high crankcase pressure and horizontal layout. The aim is to keep oil around the oil pick-up pipe, where it is needed, so it can be distributed around the engine.

When cornering at speed, oil can work its way out of the sump and flow across to the cylinder head castings, leaving less oil around the pick-up pipe. The pick-up pipe draws oil from the sump and feeds the oil galleries, keeping moving components lubricated and cool. If oil is not available to the pick-up pipe, many areas of the engine go without lubrication, temperatures rise and components ultimately fail.

The kit includes a Stage X baffled sump, which puts a "lid" on the container holding the engine oil, so that when the car's momentum is thrown to one side, the oil stays in its designated area.

On a standard engine, oil vapours from the crankcase and cylinder heads are usually recycled back through the air intake system. The downside is that the intake hoses, turbo, intercooler and connecting pipework can build up oil over time, which slows air flow, reduces cooling ability and causes general wear.

A catch tank kit vents all excess vapours into a separate tank, where the oil is separated from the damp air before being returned directly to the sump. This keeps the engine's breathing system clean and free of oil residue for maximum efficiency, and is especially useful on high-performance or tuned engines, where dense oil vapour can hurt performance.

The kit includes all the corresponding parts needed for a complete installation, plus an oil drain hose between the catch tank and the sump, so oil is not left to fill the tank and is returned to the engine.

Unlike universal tanks, Stage X tanks are made specifically for the Impreza, for easy, straightforward fitment and a factory appearance.