Parts for your 2020 Subaru Impreza-Oil cap

2020 Subaru Impreza Oil Cap: What It Does and How to Look After It

According to the 2020 Subaru Impreza Owner’s Manual (Maintenance and service – Engine oil) and the Subaru FB20 engine service literature (Lubrication section), the Impreza is fitted with a standard threaded oil filler cap on the FB20 2.0‑litre boxer engine. It’s the point under the bonnet where engine oil is added and it’s essential to normal operation, not an optional or redundant part.

The oil cap’s job is straightforward but vital. It seals the top of the engine’s oil filler neck, keeping dust and moisture out, preventing oil vapour and splash from escaping, and helping maintain correct crankcase ventilation. Many caps on this model are marked “0W‑20”, reminding owners of the specified full‑synthetic grade recommended by Subaru in this generation.

As part of regular servicing of a 2020 Subaru Impreza, the oil cap deserves a quick once‑over. A tired cap or perished seal can mist oil around the rocker cover area, leave a faint burning‑oil smell, or, if left loose, allow unmetered air into the crankcase ventilation path, potentially upsetting idle quality and fuel trims.

• Inspect at every service (about every 12 months/12,500 km in AU/NZ): check the cap body for cracks and the rubber O‑ring for flattening, hardening, or splits.
• Wipe the filler neck and cap threads clean before refitting, a light film of fresh oil on the O‑ring helps sealing.
• Refit by hand only—turn anti‑clockwise to start if it feels cross‑threaded, then tighten clockwise until snug. No tools needed.
• If the cap is lost or won’t seal, don’t keep driving, fit a correct replacement promptly to avoid oil spray and contamination.

Replacement is simple and inexpensive. Using a genuine Subaru cap (or a quality equivalent specified for the FB20 engine) ensures the correct fit and seal profile. Caps are typically supplied with a new O‑ring, if not, replace the O‑ring at the same time. Workshop techs will also confirm that the PCV system hoses and the cam cover area are dry, so any oil weep is not misdiagnosed as a cap issue.

Owners chasing tidy, trouble‑free motoring can treat the oil cap as a small but important piece of preventative maintenance—keep it clean, intact, and properly tightened, and it’ll quietly do its job for years.

FAQs

Where is the oil cap on a 2020 Subaru Impreza?
It sits on top of the engine under the bonnet, on the driver’s side of the plastic engine cover for most right‑hand‑drive cars. It’s a round, twist‑off cap marked with the oil symbol and often “0W‑20”.

What oil grade should the cap specify, and how tight should it be?
Subaru specifies 0W‑20 full‑synthetic for the FB20 engine, which is commonly printed on the cap. Tighten the cap by hand until it seats and is snug—no tools, and don’t over‑tighten.

Can a loose or missing oil cap cause issues?
Yes. A loose or missing cap can leak oil, cause smells or light smoke from oil on hot parts, and may upset crankcase ventilation enough to affect idle quality. If the cap’s missing, stop the engine and fit the correct cap before further driving.