The Toyota GR86 has quickly become a favorite among driving enthusiasts thanks to its lightweight chassis, sharp handling, and affordable price tag. However, like its predecessor the Subaru BRZ, the GR86’s FA24 flat-four engine runs hot during aggressive driving, especially on track days or in hot climates. Without adequate oil cooling, sustained high-rpm driving can push oil temperatures past 260°F, causing viscosity breakdown, reduced lubrication, and eventually engine damage. Installing a dedicated oil cooler like the Mishimoto kit is one of the most effective upgrades you can make to keep your GR86 reliable and performing at its peak. This guide covers the complete installation process, the total cost involved, and the real-world benefits of this popular modification.

Why Oil Temperature Matters for the GR86’s FA24 Engine

The Subaru-built FA24 in the GR86 is a high-compression, 2.4-liter boxer engine with direct injection. It produces 228 horsepower stock, but its cooling system was designed primarily for street use. When you push the car hard on a road course or canyon road, the oil quickly becomes the weak link.

Engine oil has a optimal operating window typically between 195°F and 225°F. Above that range, the oil’s viscosity drops, the lubricating film thins, and thermal breakdown accelerates. Extended exposure to temperatures above 280°F can lead to coking, sludge formation, and accelerated bearing wear. The GR86’s stock oil cooler (a small water-to-oil unit built into the water pump housing) simply isn’t enough for sustained high loads. An aftermarket air-to-oil cooler like the Mishimoto unit provides much greater thermal mass and more surface area to radiate heat, keeping oil temperatures stable.

Many GR86 and BRZ owners on forums like gr86.org report dropping peak oil temps by 30–50°F after installing a proper oil cooler. This not only protects the engine but also allows you to drive harder for longer without worrying about limp mode or oil pressure drops.

Benefits of a Mishimoto Oil Cooler

Mishimoto is a well-known brand in the aftermarket cooling world, and their GR86-specific kit is designed for a direct-fit installation. Here are the key advantages:

  • Engine Protection: By keeping oil temperatures in the safe zone, the cooler reduces wear on bearings, piston rings, and the oil pump itself. This is especially critical for track-driven cars where heat cycles are extreme.
  • Consistent Oil Pressure: Thinner oil due to heat leads to lower oil pressure. The cooler helps maintain pressure within the factory spec, ensuring proper lubrication at high rpm.
  • Peak Performance Retention: When oil is too hot, the ECU may pull timing or trigger a power-reducing fail-safe. A cooler prevents this, letting you enjoy full power lap after lap.
  • Extended Oil Life: Lower oil temperatures slow oxidation and additive depletion, so you can safely extend your oil change intervals (though regular changes are still recommended).
  • Track-Ready Reliability: Many GR86 track enthusiasts consider an oil cooler essential equipment. It’s one of the first upgrades recommended by professional driving instructors and race shops.
  • Premium Build Quality: Mishimoto’s kit uses a bar-and-plate core, AN fittings, and stainless steel braided lines. It comes with a lifetime warranty, adding peace of mind.

Cost Breakdown: What to Expect

Depending on where you buy, whether you install it yourself, and any optional accessories, the total cost can vary. Below is a realistic breakdown:

  • Mishimoto Oil Cooler Kit (GR86/BRZ): List price ranges from $400 to $550. You can often find sales or coupon codes from vendors like Mishimoto’s own store, or from retailers like Import Image Racing or FTspeed. The kit includes the cooler, bracket, lines, fittings, and thermostat sandwich plate adapter.
  • Optional Thermostat: The standard kit usually includes a thermostat (Mishimoto uses a 185°F opening unit). If you buy a base kit without one, add $40–$80 for a separate thermostat plate. Highly recommended for street driving to bring oil up to temp faster.
  • Professional Installation: Shop labor rates vary. Expect $200–$400 for a specialized Japanese performance shop, or $100–$200 from a general mechanic if you already have the bumper removed. DIY saves this entirely.
  • Engine Oil & Filter: You’ll need fresh oil and a new filter for the install. Budget $50–$70 for 5W-30 synthetic oil (Mobil 1, Motul, etc.) and an OEM or Wix filter.
  • Miscellaneous: Zip ties, heat shrink, extra clamps, or a cutting tool for the plastic shroud might add another $20–$40.

Total estimated cost: $470 to $1,060, with the average DIY install coming in around $500–$600. That’s a small price for the peace of mind that your GR86’s engine will survive track days.

Installation Guide: Step-by-Step

This guide assumes you have intermediate mechanical skills and a basic socket set. Always work on a cool engine with the car safely raised on jack stands. Allow at least 3–4 hours for the first-time install.

Tools & Supplies

  • Socket set (10mm, 12mm, 14mm, 17mm)
  • Combination wrenches (12mm, 14mm, 17mm)
  • Torque wrench (ft-lb and in-lb ranges)
  • Oil catch pan
  • Jackstands and floor jack
  • Trim removal tools (plastic pry tools)
  • Flathead screwdriver
  • Cutting tool (Dremel with cutting wheel or snips for lower grille removal, if needed)
  • Funnel and shop towels
  • Safety glasses and mechanic gloves

Step 1: Preparation & Drain Oil

Park on level ground. Remove the oil filler cap (this helps with draining). Raise the front of the car and place securely on jack stands. Remove the under-engine splash shield (12mm bolts). Place the catch pan under the drain plug. Remove the drain plug (17mm) and let the oil fully drain. While draining, remove the oil filter (it’s accessible from underneath on the passenger side) and let the old oil drain as well.

Step 2: Remove the Front Bumper

The Mishimoto kit mounts in front of the radiator, requiring bumper removal for clearance. Start by removing the clips holding the upper radiator cover. Then remove the pop-clips on top of the bumper (two on each side near the headlights). Open the hood and pull the top clips from the bumper bracket. Next, remove the four 10mm bolts securing the bumper to the fender liners (two per side). Pull the lower edge of the bumper outward to release the side clips. Disconnect the fog light connectors if equipped. Carefully lift the bumper off and set it aside on a soft surface.

Step 3: Remove the Lower Grille Duct (If Needed)

On GR86s, the lower center plastic shroud that directs air to the radiator can interfere with the oil cooler’s placement. You may need to cut a section with a Dremel or use a snips to create clearance for the cooler fittings. Mishimoto’s instructions are designed to require minimal trimming, but check the trail fit first.

Step 4: Install the Oil Cooler Adapter (Sandwich Plate)

Locate the factory oil filter mount on the engine block. Unscrew the old oil filter adapter (a large 24mm or 27mm nut, depending on year; use a crow’s foot wrench if needed). The Mishimoto sandwich plate replaces this. Apply a light coat of oil to the gaskets and thread the sandwich plate onto the block. Torque to 22–25 ft-lb. Then screw the provided banjo bolts into the ports on the sandwich plate for the oil lines. Important: Ensure the thermostat position aligns correctly when cold (the thermostat stays closed until 185°F).

Step 5: Mount the Oil Cooler

Mishimoto provides a custom bracket that bolts to the crash bar. Remove the two 14mm bolts from the crash bar (behind the radiator). Mount the bracket using these bolts, then slide the oil cooler onto the bracket’s studs and secure with the supplied lock nuts. The cooler should sit in front of the AC condenser, positioned to maximize airflow. Use a level to ensure it’s straight.

Step 6: Route the Oil Lines

Route the stainless braided lines from the sandwich plate up to the cooler. Avoid sharp bends or contact with hot surfaces (exhaust manifold, radiator hoses). Use the supplied nylon wire ties to secure the lines away from moving parts. The typical routing goes up the passenger side of the engine bay, across the top of the radiator, then down to the cooler fittings. Mishimoto recommends using the manufacturer’s hose routing guide for best results. Leave a small loop for engine movement. Torque the AN fittings to the cooler ports snugly—do not overtighten, but ensure the O-rings are seated.

Step 7: Reinstall Bumper & Splash Shield

Before refitting the bumper, spin the oil filter on (hand-tight only) and torque the drain plug to 30 ft-lb. Replace the splash shield. Carefully reinstall the bumper, aligning the side clips and pushing firmly. Reinstall the 10mm bolts and pop-clips. Reconnect the fog lights.

Step 8: Refill Oil & Bleed the System

Lower the car. Add new oil—capacity is approximately 5.5 quarts for the FA24 with the cooler and lines. Start with 5 quarts, run engine for 30 seconds, then check dipstick and add more as needed. While the engine is running, look for leaks at all fittings. The oil cooler will fill; the thermostat may prevent immediate circulation, but after a few minutes at idle, the core should become warm to the touch. Rev the engine gently to 2500 rpm to help bleed air from the lines.

Step 9: Test & Monitor

Take the car for a short test drive (5–10 miles) on a mix of street and freeway. Watch the oil temperature gauge (or aftermarket sensor if you added one). On a 70°F day, oil temp should stabilize around 200–210°F. If it stays below 180°F, the thermostat may be stuck open—but this is rare. After the drive, recheck for leaks. Check oil level again after the system has fully circulated.

Post-Installation Checks & Maintenance

After the first track day or 500 street miles, inspect the oil cooler lines and fittings for tightness. The initial heat cycles can cause slight expansion. Also check the mounting bracket bolts—Mishimoto recommends re-torquing after one heat cycle. Change the oil and filter after the first track day to flush any debris that might have entered during installation.

Consider installing an oil temperature and pressure gauge if you don’t already have one. The GR86’s factory gauge is not real-time. A simple OBD2 reader can display coolant temp, but you’ll want dedicated oil temp monitoring for peace of mind.

Alternatives & Considerations

While Mishimoto’s kit is excellent, there are other options on the market. Setrab and CSF make universal coolers, but require custom brackets and lines. The benefit is greater core volume, but installation is more involved. Perrin offers a similar “dual oil cooler” system that replaces the OEM heat exchanger, but it costs more. The Jackson Racing kit is also popular, though it mounts lower and can be more prone to damage. For most street and track use, the Mishimoto kit offers the best value: complete kit, lifetime warranty, and proven results.

One important consideration: an oil cooler will delay the time it takes for engine oil to reach full operating temperature on cold days (the thermostat helps, but it’s still slower than stock). If you drive in freezing climates, you may want to block part of the cooler in winter with a simple cover. Also, be aware that a bigger cooler adds weight—about 5–6 lbs total—but the reliability benefits far outweigh that.

Final Thoughts

Installing a Mishimoto oil cooler on your Toyota GR86 is one of the best investments you can make for long-term engine health and track-day confidence. The installation is straightforward for a DIY mechanic with average tools, and the total cost is reasonable. With oil temps under control, you’ll be able to enjoy the GR86’s phenomenal handling without worrying about heat soak or engine knock. Whether you’re a weekend warrior or a novice looking to get into HPDE events, this upgrade will pay for itself in reliability and peace of mind.

For more information on the specific kit and installation tips, visit Mishimoto’s product page. And don’t forget to join the GR86 community on forums to share your experience and learn from others who have done the same mod.