Causes of Excessive Oil Consumption

2013–2015 Subaru Outbacks have often been reported to experience excessive oil consumption, primarily due to engineering and manufacturing issues. Here are some of the main reasons:

• Piston Rings: The primary cause of excessive oil consumption in these models is often linked to the piston rings, which may not seal properly. If the piston rings are not functioning correctly, oil can pass into the combustion chamber and burn at a higher rate, leading to excessive consumption of oil.
• PCV Valve Malfunction: The Positive Crankcase Ventilation (PCV) valve can sometimes fail or become clogged. This valve is essential for reducing crankcase pressure and recycling air and fuel. When it malfunctions, it can lead to increased oil consumption by allowing more oil fumes to escape into the engine intake.
• Engine Design: Subaru's Boxer engine design can inherently consume more oil since its horizontal layout can cause oil to linger near the pistons and rings, potentially leading to higher than average consumption.
• Oil Viscosity: The use of inappropriate oil viscosity may contribute to higher oil usage. Subaru recommends specific oil types for these vehicles, and using oil with different viscosity can affect consumption rates.

Addressing the Oil Consumption Issue

To address the excessive oil consumption in the 2013–2015 Subaru Outbacks, several solutions can be implemented:

• Piston Ring Replacement: One of the most effective solutions is replacing or repairing the piston rings. This, however, is a significant repair and often requires a skilled mechanic, due to the complexity and cost involved.
• PCV Valve Inspection and Replacement: Regular inspection of the PCV valve for proper operation or clogs can help prevent oil consumption problems. Replacing a faulty PCV valve can sometimes mitigate the issue.
• Use of Correct Oil Grade: Always use the manufacturer's recommended oil grade and change it at the intervals specified by Subaru. This ensures that the engine operates optimally and reduces the likelihood of excessive oil burning.
• Oil Consumption Test: Conduct an oil consumption test as recommended by Subaru and dealers. This test can confirm whether your Outback is consuming excessive oil and determine the appropriate course of action based on warranty or service bulletin mandates.
• Technical Service Bulletins (TSBs) and Recalls: Check if there are any TSBs or recalls related to your Outback model regarding excessive oil consumption. Subaru has issued guidance in the past for addressing this issue under warranty, which may still be applicable.

Owners experiencing excessive oil consumption should remain vigilant about their vehicle's oil levels and maintain regular service intervals. If an issue persists or worsens, consultation with a trained Subaru technician is recommended for professional evaluation and repair.