Subaru turbo filter
This applies to all Subaru vehicles equipped with a turbocharger. It is possible that the turbo oil supply mesh filter, which is located inside the banjo bolt that secures the turbocharger oil supply pipe to the rear of the right side cylinder head, may become clogged, thereby preventing oil supply to the turbo, resulting in failure. It is required that this filter screen be checked for obstructions whenever a turbocharger is being replaced for a failure.
If the mesh filter screen is found to be obstructed, it must be cleaned or replaced. Obstructions can include sludge due to poor engine oil maintenance or harsh driving conditions. Further diagnosis may be required if significant amounts of sludge are found in the mesh screen. In any turbocharger replacement, sufficient oil pressure to the turbocharger must be verified.
The mesh filter screen is only available with a replacement banjo bolt (P/N 14445AA090). The tightening torque for this banjo bolt is 21.4 ft.-lbs. (29 Nm). Whenever the bolt is removed or replaced, both copper washers must also be replaced. Make sure that the mesh filter screen is installed in the proper direction, since improper orientation will prevent oil supply to the turbo.
Do not confuse the turbocharger oil supply mesh filter screen with the Active Valve Control System (AVCS) union screw mesh filter screen.
In addition, if the turbo is replaced, it is required that the oil pan be removed to inspect for sludge, metal and other debris. If found and not removed, catastrophic engine damage could occur. Also check oil supply lines, oil passages, and look for a restricted oil filter.
Due to heat generated by the turbo and carbon deposits contained in exhaust gas, the oil in a turbocharged engine will deteriorate faster than the oil in a naturally aspirated engine. Therefore, all turbocharged vehicles are classified as “severe driving condition” vehicles. The recommended oil and filter change interval for turbocharged engines is 3,750 miles or four months, whichever comes first.