Checked oil specs by engine
2021 Subaru WRX STI oil capacity, type & filter
The 2021 Subaru WRX STI takes 4.5 qt of 5W-30 oil.
Applies to checked engine: 2.5L 4-Cyl Turbo. Also check 2021 Subaru WRX .
PRO-TEC PXL57712 is copied into the checkout checklist below. Other listed filters are source-backed alternatives.
Search paths only — confirm your OEM viscosity spec and quantity before checkout.
2021 Subaru WRX STI oil specs: capacity conditions and filter notes
All listed filter part numbers are compatible alternatives for your vehicle. Choose any one brand, then confirm the exact part number at checkout.
With filter means the volume includes a new filter. Service fill is the typical drain-and-fill amount. Dry fill is for a fresh empty engine only.
Retailer fitment tools may use different data. Confirm oil capacity, viscosity, and filter part number before ordering.
Source coverage for the 2021 Subaru WRX STI
Supported by Pennzoil OATS, AMSOIL Lookup, and Castrol (Olyslager).
Supported by Pennzoil OATS, AMSOIL Lookup, and Castrol (Olyslager).
Supported by K&N Filters, Purolator Part Finder, RockAuto, and AMSOIL Lookup.
6 checked source rows for the 2021 Subaru WRX STI.
Before ordering for this 2021 Subaru WRX STI
- Capacity
- 4.5 qt (Service fill)
- Oil type
- 5W-30
- Filter
- PRO-TEC PXL57712
Source check: Last checked 2026-06-27 from RockAuto, Pennzoil OATS, K&N Filters, Purolator Part Finder, AMSOIL Lookup, and Castrol (Olyslager).
Subaru WRX STI oil specs by year
This table includes checked Subaru WRX STI model years available in our database.
| Year | Capacity | Oil type | Filter |
|---|---|---|---|
| 2021 Current page | 4.5 qt | 5W-30 | PRO-TEC PXL57712 |
| 2020 | 4.5 qt | 5W-30 | AMSOIL EA15K12 |
| 2019 | 4.5 qt | 5W-30 | CHAMP / LUBER-FINER PH2876 |
| 2018 | 4.5 qt | 5W-30 | AMSOIL EA15K12 |
| 2017 | 4.5 qt | 5W-30 | AMSOIL EA15K12 |
| 2016 | 4.5 qt | 5W-30 | AMSOIL EA15K12 |
| 2015 | 4.5 qt | 5W-30 | AMSOIL EA15K12 |
How we verified 2021 Subaru WRX STI oil data
How we verify fitmentChecked fitment data. Last checked: 2026-06-27.
This page checked 6 sources for the 2021 Subaru WRX STI. The table lists which checked source contributed capacity, oil type, or filter evidence.
We checked leading oil brands and aftermarket filter catalogs so you don't have to.
- Confidence
- Verified fit
- Sources checked
- 6
- Last checked
- 2026-06-27
- Capacity: Pennzoil OATS, AMSOIL Lookup, and Castrol (Olyslager)
- Oil type: Pennzoil OATS, AMSOIL Lookup, and Castrol (Olyslager)
- Filter: K&N Filters, Purolator Part Finder, RockAuto, and AMSOIL Lookup
| Source | Supports | Checked | Link |
|---|---|---|---|
| RockAuto | Filter | 2026-06-27 | Checked source |
| Pennzoil OATS | Capacity, Oil type | 2026-06-27 | Visit brand site |
| K&N Filters | Filter | 2026-06-27 | Visit brand site |
| Purolator Part Finder | Filter | 2026-06-27 | Visit brand site |
| AMSOIL Lookup | Capacity, Oil type, Filter | 2026-06-27 | Visit brand site |
| Castrol (Olyslager) | Capacity, Oil type | 2026-06-27 | Visit brand site |
2021 Subaru WRX STI oil FAQ
Is the oil capacity measured with or without the filter?
Capacity condition matters. With filter includes a new filter. Service fill is the typical drain-and-fill amount. Dry fill is for a fresh empty engine only.
Why should I confirm before buying?
Retailer catalogs can update separately. Confirm the exact 2021 Subaru WRX STI selector at checkout before you buy.
Do I also need to match the OEM oil approval?
Yes. Viscosity is only one part of the oil spec. Match the oil approval listed in your owner's manual or on the bottle before checkout.
How often should I change the oil on a 2021 Subaru WRX STI?
Use the oil-life monitor or the interval in your owner's manual for this engine. Severe service can require a shorter interval.
Do I need a new drain plug gasket?
Replace it when your vehicle uses a serviceable gasket or crush washer. Confirm the gasket size and drain plug torque from the service manual or parts counter.
2021 Subaru WRX STI maintenance checklist
One part checked. Look up the rest while you're here.
Where to buy
These are retailer search paths for your vehicle's oil and filter specs. Verify final fitment at checkout.
This section may include affiliate or sponsored retailer links. They are purchase paths, not fitment evidence.
Walmart
Compare oil and filter listings for the 2021 Subaru WRX STI. Confirm capacity, viscosity, and filter part number before checkout.
Search 2021 Subaru WRX STI oil & filter →AutoZone
Use AutoZone's vehicle selector for the 2021 Subaru WRX STI before checkout to confirm oil capacity, viscosity, and filter fitment.
Search 2021 Subaru WRX STI oil & filter →Amazon
Search Amazon listings for the 2021 Subaru WRX STI and check listing fitment notes against the specs above.
Search 2021 Subaru WRX STI oil & filter →O'Reilly
Open O'Reilly's fitment search for the 2021 Subaru WRX STI and verify oil capacity, viscosity, and filter part number before ordering.
Search 2021 Subaru WRX STI oil & filter →Look up another vehicle
Find checked oil capacity, type, and filter data by exact year, make, and model.