2017 Subaru Forester: Transmission Fluid & Service

Quick answer

• Transmission make/model: Lineartronic TR580 CVT
• OEM fluid spec: Subaru High Torque CVT Fluid (SOA748V0200)
• Drain & fill capacity: 5.5 - 6.0 quarts (approximate)
• Full overhaul capacity: 12.9 - 13.5 quarts
• Filter OEM part number: Verify with dealer or service manual; internal and not typically serviced during a fluid change.
• Recommended service interval: 60,000 miles (normal duty); 25,000 miles (severe duty)

Fluid type explained

The 2017 Subaru Forester is equipped with a Lineartronic TR580 Continuously Variable Transmission (CVT). Unlike traditional automatic transmissions with fixed gear ratios, a CVT uses a steel belt or chain and a pair of variable-width pulleys to provide a seamless range of ratios. This design requires a very specific fluid to function correctly. The OEM-specified fluid is Subaru High Torque CVT Fluid (SOA748V0200). It is crucial to use only this fluid or an aftermarket equivalent that explicitly meets this specification. Using incorrect fluid, such as standard ATF, will lead to slipping, shuddering, and eventual transmission failure. These specialized CVT fluids are formulated with unique frictional characteristics to ensure proper clamping force between the belt/chain and pulleys, and they also contain additives to protect against wear and oxidation.

Service procedure

There are two primary methods for servicing the transmission fluid in your Forester: a drain and fill, or a full fluid exchange.

• Drain and Fill: This is the most common and straightforward method. It involves removing the drain plug on the transmission pan, allowing approximately 5.5 to 6.0 quarts of fluid to drain out, and then refilling with the same amount of new fluid. While this is a relatively simple procedure, it only replaces about half of the total fluid in the transmission. The rest of the old fluid remains in the torque converter and other internal components. For this reason, some technicians recommend performing a series of three drain and fills to exchange a higher percentage of the old fluid.

• Full Fluid Exchange: A full fluid exchange is a more thorough process that uses a specialized machine to pump out all of the old fluid while simultaneously refilling with new fluid. This method replaces nearly 100% of the transmission fluid and is the preferred method for ensuring the longevity of your CVT. This service should only be performed by a qualified technician with the proper equipment.

The TR580 CVT has an internal fluid strainer. This strainer is not a typical serviceable filter and is only replaced during a complete transmission overhaul.

Service interval

Subaru's recommended service interval for the transmission fluid can vary based on how the vehicle is used.

• Normal Duty: For most drivers, Subaru recommends a transmission fluid inspection every 30,000 miles, with a replacement at 60,000 miles.

• Severe Duty / Towing: If you frequently drive your Forester in stop-and-go traffic, in mountainous terrain, at high speeds in hot weather, or use it for towing, you are operating under severe duty conditions. For these situations, the recommended service interval is shortened to every 25,000 miles.

Adhering to the severe duty schedule is a wise investment in the longevity of your transmission, especially considering the high cost of CVT replacement.

Common transmission problems

The Lineartronic TR580 CVT is generally a reliable transmission, but some common issues have been reported.

• Torque Converter Clutch (TCC) Solenoid Failure: One of the most common problems is a failure of the TCC solenoid. This can cause a shudder or vibration, particularly when accelerating at low speeds. In many cases, the check engine light will illuminate with a corresponding trouble code.

• Valve Body Issues: The valve body is the hydraulic control center of the transmission. Issues within the valve body can lead to a variety of symptoms, including delayed engagement, harsh shifting, or a complete loss of drive. Often, this requires replacement of the entire valve body assembly.

• Fluid Leaks: While not as common, leaks can develop from the transmission pan gasket, axle seals, or cooler lines. Any fluid leak should be addressed immediately, as low fluid level will quickly lead to catastrophic transmission damage.

Being proactive with fluid services and addressing any unusual symptoms promptly is the best way to avoid major repairs. If you notice any issues with your 2017 Subaru Forester's transmission, it's best to have it inspected by a qualified technician.

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