The 2018 Subaru Legacy uses different oil viscosities depending on the engine: 0W-20 synthetic for the 2.5-liter engine, and 5W-30 synthetic for the 3.6-liter engine.
In 2018, Subaru offered two engine options for the Legacy—the 2.5-liter FB25 flat-four and the 3.6-liter EZ36 flat-six. The oil grade is specified by engine type, and using the correct viscosity helps with lubrication, cold starts, and overall engine longevity. Always refer to the owner’s manual or speak with a Subaru technician if you’re unsure about which engine your model has.
Engine options and oil requirements
To help clarify, here are the oil types recommended by Subaru for each engine.
- 2.5-liter FB25 engine: 0W-20 synthetic oil. Approximate capacity: about 4.5–4.6 quarts (with filter).
- 3.6-liter EZ36 engine: 5W-30 synthetic oil. Approximate capacity: about 6.9 quarts (with filter).
Note: Actual capacity can vary with oil filter size and whether you include a drain plug washer; always verify with the owner's manual or service bulletin.
2.5-liter FB25 engine
The 2.5L FB25 engine in the 2018 Legacy is designed for efficiency and typically uses 0W-20 synthetic oil. This viscosity supports good cold-start performance and fuel economy. When performing an oil change, plan for roughly 4.5–4.6 quarts of oil plus a new filter, though exact figures can vary by model and filter type. Use a synthetic 0W-20 oil that meets Subaru’s specifications and API standards.
3.6-liter EZ36 engine
The 3.6L EZ36 engine requires 5W-30 synthetic oil. The oil capacity, including the filter, is around 6.9 quarts. This engine can benefit from a slightly thicker viscosity at higher temperatures, which 5W-30 provides. Use synthetic 5W-30 oil that meets Subaru’s specifications and API standards.
Practical tips and maintenance reminders
Always verify the precise capacity and oil specification in your vehicle’s owner’s manual, as production changes or regional requirements can affect recommendations. If you live in extreme climates (very cold or very hot), consult the dealer or Subaru service literature for any approved alternatives to the standard viscosities.
Summary
For the 2018 Subaru Legacy, oil type depends on the engine. The 2.5-liter FB25 engine uses synthetic 0W-20, with an approximate capacity of 4.5–4.6 quarts with a filter. The 3.6-liter EZ36 engine uses synthetic 5W-30, with an approximate capacity of 6.9 quarts with a filter. Always confirm exact specifications in the owner’s manual and adhere to climate-related recommendations when selecting oil.