Parts for your 2020 Subaru Legacy-Head gasket

2020 Subaru Legacy head gasket: what it is, why it matters, and when to act

Yes, the 2020 Subaru Legacy absolutely uses a head gasket. Technical references such as the Subaru Factory Service Manual for the 2020 Legacy/Outback platform (FB/FA engine sections) and the Subaru Genuine Parts Catalogue list a “Cylinder Head Gasket” for both the 2.5‑litre FB25 and the 2.4‑litre turbo FA24F engines. These late‑model boxers run multi‑layer steel (MLS) gaskets designed to seal combustion pressure while keeping engine oil and coolant where they belong.

In this car, the head gasket sits between each aluminium cylinder head and the engine block, coping with big temperature swings and pressure loads every time the driver hits the starter. Its day job is threefold: seal the combustion chambers so the engine makes proper power, keep the coolant circuit sealed so temps stay in the green, and separate oil galleries so lubrication stays clean. The newer FB/FA engines brought gasket and cooling updates over older EJ‑series motors, improving durability when serviced on time and kept cool.

• Common warning signs drivers notice: unexplained coolant loss, overheating under load, bubbles in the expansion tank, white exhaust steam after warm‑up, sweet smells, or milky residue under the oil filler cap.
• Best care tips: stick to the logbook schedule, use the correct Subaru Super Coolant (blue, long‑life) and the specified engine oil, and never keep driving if the temperature gauge spikes.

If replacement is needed, it’s a specialist job. Many workshops remove the engine for access on Subaru boxers, which makes it easier to clean gasket surfaces, check head flatness, and pressure‑test the heads. Quality MLS gaskets, fresh head bolts where specified, and the exact Subaru torque/angle sequence from the service manual are must‑dos. It’s also smart to replace ancillary items while it’s apart—thermostat, coolant hoses, and, if mileage suggests, timing components and the water pump—so the owner isn’t paying for the same labour twice. A reputable Subaru technician will also perform a cooling‑system block test and a cylinder leak‑down test before pulling it down, confirming the diagnosis and ruling out simpler culprits like a weak radiator cap or tired expansion hose. Treated well and kept cool, the 2020 Legacy’s head gasket should give years of quiet service across heaps of kilometres.

FAQs

Do 2020 Subaru Legacy models still have “head gasket issues” like older Subarus?
No. The FB25 and FA24F engines use improved MLS gaskets and revised cooling paths. While any engine can fail if overheated or neglected, the 2020 model’s design has a far lower incidence than earlier EJ‑series vehicles when serviced correctly.

What are the earliest signs of a head gasket problem on a 2020 Legacy?
Watch for rising temps on climbs, persistent coolant loss without visible leaks, bubbles in the expansion tank after warm‑up, or a sweet exhaust smell. A workshop can verify with a chemical block test and a leak‑down test.

Should the head bolts be replaced during a head gasket job?
Subaru’s service procedures specify using the correct torque/angle method and replacing bolts where required. Most pros fit new head bolts on FB/FA engines as good practice to ensure consistent clamping on the MLS gasket.