Developing a High-Performance Oil Cooler for the Subaru BRZ / Toyota 86
As is commonly known, an oil cooler is a key modification to improve the reliability of your car on track and even on the street. Being based in Queensland, Australia our summers get to the mid to high 30 degrees Celsius, combine that weather with pushing your car on track, we can see oil temperatures well in excess of 120 degrees. Whilst the new FA24 engine does have a coolant to oil heat exchanger, it is immediately overwhelmed when taken on track, making a dedicated oil cooler a necessity.
We began our oil cooler development because we saw that there was no affordable solution in the market, and it didn’t make sense to us why some brands were charging $1500+ (AUD) for a kit. Going into this, we wanted to develop something more affordable but was equally or better performing and be backed by real world data and on track testing.
Understanding the Problem
The problem is pretty simple, pushing the cars hard on track overheats the oil well past the standard operating temperature.
High oil temperature leads to a few issues:
- As the temperature increases, so does the oils viscosity, often outside the operating window. This thinning of the oil means the engine gets less protection, especially from the already thin 0W-20 oil which the FA20/25's require.
- Oil pressure decreases due to the increase in viscosity, and we all know the oil pressure issues which have been well documented with the FA24 engines.
- As oil goes through more high temp cycles, it breaks down the lubricating and cleaning chemicals within the oil and further reduces its effectiveness.
Setting the Design Goals
Before throwing the wallet and time at designing a solution, we had come up with the goals of the project:
- Stabilise oil temps to keep the the oil from not going past 115C
- Avoid overcooling on the street by integrating a thermostatic sandwich plate.
- Be affordable but also have options for those who want the best solution for track performance.
- Clean fitment and easy installation on a stock car.
Component Selection
Oil Cooler Core
For the kit we’ve decided to provide a few options for core:
- 12 Row - the cheapest setup, adequate for street use with limited track running in cooler climates.
- 17 Row - the mid-tier setup, for those looking to track their car more regularly or in warmer climates.
- 14 Row PWR - for those doing regular track driving or endurance events. PWR is a well-known performance cooling manufacturer and are based here in Brisbane. They make a lot of cooling products for motorsport teams across a range of series including F1, WEC, Dakar, and WRC. Their proprietary "fluted" design within the core allows for higher heat transfer between the oil and cooler due to its larger surface area. This is the core we used to collect data on our BRZ as seen in the blog.
Thermostatic Plate
In order to make our kits as versatile as possible we include a thermostatic oil cooler sandwich plate. This means that the thermostat opens and oil only flows through the sandwich plate and into the cooler at 80 degrees Celsius. This system means that the car is still able to warm up to normal operating temperature quickly and lets the engine maintain the minimum oil temperature it needs in cooler climates. In addition to this, our sandwich plate includes 4 ports, two of which are used for the cooler lines but this leaves 2 ports for sensors (usually oil temperature and oil pressure) to be added with no additional hardware or products needed.
Lines and Fittings
When looking at what is on the market, we noticed a trend with companies not using full-flow fittings with oil coolers. We don’t know why they do this, and from our research it seems there are arguments that full-flow fittings are just a marketing gimmick and not necessary. Maybe these companies are saving money by not using full-flow fittings, or they don’t think it’s necessary.
From our perspective and research, there is small improvement in oil flow using full-flow over normal fittings at the edges of performance. We’ve taken the route of more oil flow is better. In addition to full-flow fittings, we decided to only use 45-degree fittings instead of 90-degree fittings that other kits use. Any aggressive bend in a fitting will reduce oil pressure so removing the need for 90-degree fittings will reduce any impacts the kit introduces on oil pressure.
For lines, we went with AN10 stainless steel braided hose with additional sheathing to protect from any potential rubbing. Pretty much every kit on the market uses AN10 so there’s no need for us to reinvent the wheel here but we believe in making our kits as durable as possible so always opt for stainless steel braiding (instead of nylon) and add an extra rubber and fiberglass insulator to stop the lines being damaged or by damaging your car as they rub against plastics and paints inside your engine bay.
Mounting Strategy
So yes, kits on the market do come with mounting bracket which helps to justify some of the additional cost. We had thought of making a bracket for our kit, however, from past experience with making our own oil coolers, track testing and many kilometres as daily drivers, we found that simply the strength from the lines and a few screws in the bottom plastic of the front tray are enough to make it mount solid (yes we have tested this to speeds above 200km/hr). There are installation benefits of this as well, as our kit requires no drilling into the crash bar, or any metal surfaces. Just four screws into the plastic radiator support tray.
Installation
Install is pretty simple and does not require removing any oil from the car. Just make sure the cars cold for obvious reasons. For the FA24, we decided to leave the factory coolant-to-oil cooler. There are some forum posts out there that removing it does improve oil pressure a little bit. This is something we may explore in the future.
Install requires the removal of the front bumper, and we recommend also removing the front passenger headlight to make life easier. After removing the oil filter, we add the sandwich plate on top and then screw and tighten the centre bolt to hold it all down. From there, we screwed the lines on and routed them down towards the front of the radiator. This will require the removal of a black bit of plastic. If you did want to put the plastic back in it would require some trimming to allow the lines to come through.
For placement of the core, we chose a central front mount and then screwed the core down. We made sure to tighten all the fittings, install the new oil filter (we used a Ryco Z411ST) and then filled the engine with more oil to account for the volume of oil which would fill the core and lines. We found about 750ml - 1L was enough. If you’ve been overfilling your oil to combat pressure drops then keep this in mind and adjust accordingly.
Checking for Leaks
After tightening everything, we started the car and checked for leaks around the filter and sandwich plate. Because the thermostat in the sandwich plate does not fully open until 80C we had to wait for the oil to reach that temperature before checking for leaks in the fittings on the lines and core. We verified everything was good and leak free before switching the car off and putting it all back together.
Track Testing
All track testing is done with our 2022 Subaru BRZ. We first ran the setup at a happy laps event run by the local BRZ/86 Car Club. This was a good opportunity to run everything in and see what the performance was like. Unfortunately, the data logging setup wasn’t ready but using the factory display in the BRZ we saw temperatures around the 105-degree range. Happy laps events don’t allow you to push the car fully, so we knew that it wasn’t the most accurate testing.
Eventually the next opportunity presented itself in the form of a proper track day with the Porsche Club out at Morgan Park Raceway in Warwick in July 2025. The data logging setup was ready to go, and we managed to capture some good data for both pressure and temperature as seen in the graphs below. Remember that this data is with the PWR 14 row core.
Note when reading lateral acceleration, negative g is when the car is turning right and positive g turning left.
Session 6 was the last session of the day but also the fastest times we saw on the K track which is the longest layout for Morgan Park at around 3km. Lap times for the session were:
| Lap Number | Time |
| 1 | 1:32.13 |
| 2 | 1:31.47 |
| 3 | 1:30.18 |
| 4 | 1:30.29 |
| 5 | 2:52.15 (in lap) |
Being in the middle of winter, the conditions were favourable for good oil temperatures, with an ambient temp of about 18 degrees. As seen in the data the max temperature we saw for the session was 109 Celsius, well within the goal of 115 we set, and with good margin going into summer where we can expect ambient temperature to be much higher than 18.
Street Performance
Driving on the street you can expect to see oil temperatures below 100 degrees, usually around the 90-degree mark but in some cases, you could get closer to 80 degrees depending on the outside temperature. If you get stuck in traffic, then oil temps will get up to 100 as there’s no airflow through the cooler core.
Reliability
We’ve been running this setup for 12 months now and have not had any issues. The car has been to about 6 track events with the setup and has performed at each and every one of them. In addition to this we have had customers attend a combined 45 events of varying intensities with our kits installed, all leak free and enjoying the cooler oil temps of course. We’ve since upgraded the cooler core on our car to something even bigger which we are experimenting with.
Conclusion
Overall, the development of our oil cooler kit was a success, and we are very pleased with the result. Whilst we would like to have captured data in summer, there are no more track events on our calendar for the year. We’ll be sure to do a follow up when we get the data. You can purchase the kit through the website. If you have any questions about the kit or feedback on the blog, please shoot us a message.