Why FA20 Turbo Engines Run Hot (and How To Fix It)

Why FA20 Turbo Engines Run Hot (and How To Fix It)

Push your FA20 turbo hard — on track, through the hills, or even in summer traffic — and oil temps skyrocket. Once your oil crosses 120–130 °C, the ECU begins pulling timing, viscosity drops, and wear increases.

This post explains why FA20 engines are prone to high oil temperatures, what happens when oil runs too hot, and how a quality oil cooler kit with thermostatic control solves the problem for good.

The Problem: Overheated Oil

Many Subaru FA20 turbo engines lack a robust factory oil cooling system. Under boost and sustained load, oil temperature rises fast — especially in tuned or hard-driven cars.

Common symptoms include:

  • Oil temp warning lamp

  • ECU pulling power at ~125 °C

  • Rough idle or increased oil consumption after heat cycles

  • Oil pressure dropping at high temp

  • Shortened oil change intervals

Why It Happens

Cause Effect
No factory oil cooler / undersized unit Heat builds without enough rejection
High boost and power output Generates excessive heat load
Heat soak in engine bay Poor airflow keeps temps high
Stop-start traffic Oil never has airflow to cool
Oil breakdown Viscosity drops, wear increases

 

The Solution: Oil Cooler Kit with Thermostat

A performance oil cooler kit adds dedicated heat rejection and thermostatic control:

  • Thermostatic sandwich plate – bypasses cooler when oil is cold, routes flow once target temp is reached. Prevents overcooling.

  • Large oil cooler core – mounted in airflow, shedding 15–25 °C under load.

  • Braided lines & AN fittings – reliable flow, no restriction.

  • Complete kit design – plug-and-play install for Subaru platforms.

Example: Fuji Racing Track Attack Kit

  • 25-row oil cooler, tested under Nürburgring conditions

  • Holds FA20 oil temps at 110–120 °C under load

  • Thermostatic plate for street & track balance

  • High-quality AN fittings, hoses, and adapters

Why Roo Racing Recommends It

  • Protects oil from thermal breakdown

  • Keeps ECU from cutting power

  • Extends oil life & service intervals

  • Essential for track days, spirited drives, and hot climates

  • Trusted brand: Fuji Racing cooling solutions are used worldwide

If you’re running your FA20 turbo beyond stock limits, oil cooling is not optional.

Roo Racing stocks Fuji Racing Oil Cooler Kits with thermostatic control — the proven fix to keep your Subaru’s oil temps safe, consistent, and track-ready.

âš¡ Built for boost. Backed by Roo.
👉 Shop Oil Cooler Kits Now

Back to blog