Caring For Your Turbo Subaru – Ruge’s Subaru

26 Dec


The turbocharger is operated by the energy contained in the exhaust gas. The exhaust gas spins a turbine inside the turbocharger at an extremely high speed (more than 100,000 rpm). That compresses the air/fuel mixture into the cylinders, which creates higher power output.

Because of the turbine’s rotational speed and the high temperature of the exhaust gas driving the turbo, proper cooling is needed to maintain durability. Engine oil plays a major role in lubricating and cooling the turbo, so following recommended oil change guidelines is important.

Proper turbocharger lubrication requires high-quality engine oil. Some oil cannot provide enough lubrication performance or durability when used in turbocharged engines. Poor-quality oil or oil not designed for turbo engines may cause damage to the turbocharger and other engine components. Consequently, it is critical to follow Subaru vehicle owner’s and service manuals for recommended oil grade and viscosity.

A second key component of the lubrication system is the oil filter. The Subaru Genuine Oil Filter, available at your Subaru dealer, is the only filter that Subaru has tested to meet requirements for filtration and flow. Aftermarket oil filters may have different filtration performance and relief-valve opening pressures, which could affect filter and engine operation. Subaru Genuine Oil Filters help ensure optimum engine and turbocharger performance.


Due to heat generated by the turbocharger 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, special care should be taken to use the proper grade oil and to monitor oil deterioration.

Under normal driving conditions, the recommended oil and oil filter change interval for turbo vehicles is every 3,750 miles or four months, whichever comes first.

However, for vehicles driven in conditions beyond normal, such as racing conditions, the oil and oil filter may require more frequent changes.


Racing-type engine stress doesn’t only occur on the track. Racing-type driving takes place when the drivetrain, suspension, and other vehicle components are used at near peak capacity. Any driving where the engine speed is kept high – either by using lower gears at higher speeds or by employing engine braking – is considered racing-type driving.

Important: A “track day” or autocross event requires an oil and oil filter change immediately before and immediately after the event. Make sure to check other engine fluid levels as well.


Check the oil dipstick periodically to make sure the oil level is within proper range, which keeps the turbocharger properly lubricated and cooled. More frequent level checks are necessary especially when utilizing engine braking, because this increases the engine’s demand for lubrication.

Important: Allowing the engine oil level to drop by more than one quart may cause oil starvation, oil pump cavitation, and bearing damage. Over time, the cumulative effect will cause turbocharger and engine failure.


Carbon deposits produced by a turbocharged engine can accumulate at the bottom of the oil pan. When changing the oil, always drain the oil through the oil drain plug hole on the oil pan. A vacuum draining device could leave carbon deposits in the oil pan and potentially contaminate the new oil.


Turbocharged Subaru engines are designed to operate on premium unleaded gasoline – 91-octane AKI or higher. This is essential for maximizing performance and is required for preventing possible engine damage.


Engine modifications such as, but not limited to, adding a boost pressure controller, using a non-genuine aftermarket air intake or exhaust system, changing the air bypass valve, “chipping,” etc., may negatively affect the warranty. Your Subaru dealer offers a line of Subaru Performance Tuning™ parts, which are designed and tested to Subaru standards and do not void the warranty.


1. Do not rev the engine or accelerate past half throttle immediately after start-up. Oil requires time to heat up for full flow, and high-rpm driving with a cold engine can damage the turbocharger.

2. After highway driving or high-load driving, allow the engine to cool by idling for at least 30 seconds before turning off the ignition.


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