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Subaru Impreza: FB20 External Head Gasket Oil Seep

FB20 External Head Gasket Oil Seep is a common engine fault on the Subaru Impreza on the 2016–2023 cars, and we rate it major. Putting it right costs $900 to $2,000 at New Zealand independent workshop rates. Below is what goes wrong, the symptoms to notice on a test drive, where to look, and what to ask the seller before you hand over any money. It is one of 44 documented faults on the Subaru Impreza.

Vehicle
Subaru Impreza
Engine
FB20
Years
2016–2023
Fuel
petrol
System
Engine

This page covers the Subaru Impreza as a model. Some faults only affect particular engines or build years — enter a plate below to narrow the list to one car.

All Subaru Impreza faults44 documented faults on this model

What you are looking at

A removed multi-layer steel head gasket held up, showing staining around the cylinder bore.Example of the part — not this vehicle

A used multi-layer head gasket. Discolouration between a cylinder and a water gallery is the tell.

John Furman · CC BY-SA 3.0 · Wikimedia Commons

What goes wrong

The FB20D horizontally-opposed engine in GK/GT Impreza is documented to develop external oil seepage from the head gasket on the exhaust side, typically between 60,000 and 130,000 km. Unlike the EJ-series coolant contamination failure, this presents as an oil film or residue along the block-to-head mating surface and can migrate down the block face. Left unaddressed it worsens as the gasket hardens; reseal requires partial engine disassembly and head surface inspection.

What you would notice

  • Visible oily residue or dark grime track along block-to-head seam
  • Oil smell from engine bay after driving
  • Slow unexplained oil level drop between services
  • Oil film on underside of engine bay or on top of exhaust manifold heat shield
  • No coolant contamination or overheating (distinguishes from EJ-series failure)

How to check it

Where to look. Engine block, head gasket mating surface, both sides of the flat-four engine

  1. With engine warm, inspect both sides of the block-to-head joint line for oil film, residue, or blackened grime tracks.

  2. Check the underside of the engine bay around the exhaust manifold flange.

  3. Look for oil accumulation on the firewall below the engine.

Parts involved: Head gasket.

What it costs to put right

$900 to $2,000 at New Zealand independent workshop rates. That is for this job on its own, not for the car.

An estimate, in NZD, for the repair as normally carried out. What a specific car costs depends on which part has failed and what it damaged on the way — treat this as the floor for a negotiation, not a quote.

Ask the seller

  • “Has the head gasket area ever been inspected or resealed, and do you have records?”
  • “How often do you check and top up the engine oil between services?”
  • “Has the car ever shown any oil residue on the engine bay floor or firewall?”

Now check the Subaru Impreza you are actually looking at

Everything above is true of the model, and it is free. What it does not tell you is whether THIS car has been looked after: its odometer history and whether the reading has ever gone backwards, whether there is still money owing on it, whether it has been reported stolen, how many owners it has had and what it is really worth today. That comes from the official records for that plate. Enter the plate for the free details, or get the full history and a market valuation from $13.49.

Not sure what you would be paying for? See what a full KickTyres check includes.

Where this comes from

The failure described above is documented in published sources — owner forums, technical service bulletins, recall notices and workshop write-ups — held in our fault database. The inspection instructions and the cost estimate are KickTyres’ own interpretation of them, and it is a starting point for an inspection rather than a manufacturer statement.

Subaru Impreza buyer questions

Is fb20 external head gasket oil seep serious on a Subaru Impreza?

We rate it major and common on the Subaru Impreza. The FB20D horizontally-opposed engine in GK/GT Impreza is documented to develop external oil seepage from the head gasket on the exhaust side, typically between 60,000 and 130,000 km. Unlike the EJ-series coolant contamination failure, this presents as an oil film or residue along the block-to-head mating surface and can migrate down the block face. Left unaddressed it worsens as the gasket hardens; reseal requires partial engine disassembly and head surface inspection.

How much does it cost to fix on a Subaru Impreza?

$900 to $2,000 at New Zealand independent workshop rates. That figure is for this job on its own. A car showing the symptoms on this page is usually worth either walking away from or negotiating down by at least the repair figure.

Which Subaru Impreza years are affected?

Our research records this fault on the 2016–2023 Subaru Impreza. Build dates move around, especially on imported cars, so treat the range as the years to look hardest at rather than a guarantee either way. The official records tell you the exact build and first registration date for the car in front of you.

How do I check for it before I buy?

With engine warm, inspect both sides of the block-to-head joint line for oil film, residue, or blackened grime tracks. Check the underside of the engine bay around the exhaust manifold flange. Look for oil accumulation on the firewall below the engine. Look here: Engine block, head gasket mating surface, both sides of the flat-four engine