Parts for your 2015 Subaru Forester-Oil cap

2015 Subaru Forester oil cap — what it does and how to look after it

Based on Subaru’s technical literature, the 2015 Subaru Forester absolutely uses an engine oil filler cap. The 2015MY Forester Owner’s Manual (engine compartment overview and Engine Oil sections) and the factory Service Manual for the FB25/FA20F engines both identify and illustrate the oil filler cap under the bonnet. Genuine parts catalogues for these engines also list the oil filler cap and its sealing ring, confirming it’s a fitted and necessary component.

On a 2015 Forester, the oil cap seals the top of the engine’s oil filler neck, keeping clean oil in and dust, moisture, and road grime out. That little cap helps maintain proper crankcase ventilation behaviour, prevents oil misting under the bonnet, and avoids drips that can bake onto hot engine parts and cause a burnt-oil odour. It’s a simple part that does a big job: sealing, protecting, and making top-ups easy.

As part of routine servicing, the oil cap deserves a quick once-over. With the engine cool, remove the cap and check that it turns smoothly, the threads or bayonet lugs aren’t chewed up, and the rubber O-ring isn’t flattened, brittle, or cracked. Wipe the filler neck and cap clean, then refit the cap hand-tight — seat it gently and snug it down without forcing it. If the cap feels loose, doesn’t seat squarely, or you notice fresh oil film around the filler area, it’s time to replace the O-ring or the whole cap.

Symptoms of a dodgy oil cap can include a faint oil smell after driving, light weeping around the filler, or a slightly rough idle from a small air leak into the crankcase. While it’s not common, an air leak here can contribute to drivability issues — so it’s worth addressing early. Use a genuine Subaru cap or a quality equivalent matched to the FB25 (2.5i) or FA20F (2.0XT) engine, a quick VIN check will confirm the correct part.

Handy tips:

• Never remove the oil cap with the engine hot — hot oil can splash.
• Replace the O-ring every few years or when it shows wear.
• A lightly oiled O-ring can help the cap seat smoothly and seal well.

Look after the oil cap during each service and it’ll quietly keep the Forester’s lubrication system clean, sealed, and drama-free.

Popular questions

Where is the oil cap on a 2015 Subaru Forester?
It’s on top of the engine under the bonnet, clearly marked and easy to spot. On most 2.5i (FB25) models it sits toward the right-hand side of the engine cover. On 2.0XT (FA20F) turbo models, it’s near the front-upper area. Either way, it’s the cap you remove to add engine oil.

Can a loose oil cap cause issues?
Yes. A loose or damaged cap can allow unmetered air into the crankcase, leading to a slight rough idle, and can mist oil around the filler area, causing odours. It’s unlikely but possible for this to contribute to fault codes if the leak is significant. Snug it properly and replace the cap or O-ring if it won’t seal.

How often should the oil cap or O-ring be replaced?
There’s no fixed interval, but it’s smart to inspect the cap at every service. Replace the O-ring when it’s flattened, hardened, or cracked, and swap the cap if it’s warped, cross-threaded, or won’t stay tight. Many owners replace the O-ring every few years as cheap insurance.