It’s been a productive 2015 year for CSF’s Racing & High Performance division, and one of our most innovative product lines so far has been our innovative “O” Series line of race-spec all-aluminum radiators with built-in oil coolers!

Subaru WRX / STI 02-07 (CSF#3076O) + Subaru WRX 08-14 / STI 08-20 (CSF#7042O)

The 1st models of this new “O” Series is for the Subaru platform: 02-07 STI/WRX (CSF #3076O),  08-14 WRX and 08-20 STI (CSF #7042O). These 2 applications were developed alongside industry leading Subaru engine builders & race tuners, LIC Motorsports from Northern California. CSF also reached out to one of our closest race teams, Subaru tuners, and dealers; Snail Performance, to help with fitment and performance testing in the hot Arizona desert they are regionally located in.

Tech Specs

  • These radiators utilize a 2-row 42mm core that features CSF’s exclusive B-tube technology, as well as an ultra-efficient 6.5mm multi-louvered fin for maximum surface area contact, heat dissipation, and extreme performance capabilities.
  • Equipped with an all-aluminum racing style drain plug for quick and reliable fluid changes
  • CSF 1.4 Bar (20 psi) radiator cap
  • Engineered and designed to be a complete “drop-in fit” install. Works with all the OEM brackets, fittings, AC condenser, hoses, and fan shrouds (only minor trimming needed at fitting locations)
  • Featuring a robust 4-plate liquid-to-oil plate-type oil cooler built into the bottom end tank. A liquid-to-oil cooler is much more efficient than a conventional air-oil cooler. Lab-tested in CSF”s ISO certified in-house lab testing facility to reject heat better and at a faster rate than a 10-row air-to-oil cooler. In addition, by being placed in the bottom end tank, the oil temperature is regulated by the thermostat of the cooling system. Never have to worry about operating temperatures not warming up fast enough in cold weather climates.
  • Complete with 2 AN-10 male fittings and is compatible with many popular aftermarket engines and exhaust manifolds.
  • This kit comes complete with a sandwich plate and forged right angle -10 fittings made by BAT (see product update notice below – CSF was forced to switch to another top-tier company for the included sandwich plate due to the previous manufacturer’s supply chain issues)
  • Topped off with the industry’s finest 1-hour hand polish “mirror finish” for a look that matches the performance.
  • Installation of this unit will require an additional 1/4 to 1/2 a quart of oil
No expense spared with CSF’s included kit. Complete with a machined thermostatic sandwich plate made by Greddy and forged right angle -10 fittings made by BAT.

Product Update

We have switched to using the Mocal compact, lightweight, high-flow M20 x 1.5 filter sandwich plate (Mocal part #SP1F) instead of the ones made by Greddy. Apparently, there were some internal issues that prevented us from purchasing the Greddy sandwich plates from their USA distributor so we had to source this part from another manufacturer.

* 2006/2007 WRX has a much tighter fitment due to different factory oil cooler and exhaust manifold combination. To make this work with these model years, you will either need to remove the factory oil cooler and cap off the coolant line coming off the water pump and at the block and/or run aftermarket headers (as it’ll have less of a fitment issue).*

$649 $599 Introductory price
(Kit Included)

Both of these new Subaru applications are now in stock, and are available through CSF’s global distribution network and select list of exclusive dealers.


This has been one of the most challenging and difficult products for us to design. A truly collaborative effort between CSF Radiators and Jackson Racing spanning the course of more than a year in development. Our first prototype debuted at SEMA 2014, and we’re very excited to be able to showcase the first production unit at SEMA 2015 at the CSF booth in the central hall (#21555).

With over five prototypes, countless design changes, and many hours of discussions, both of our companies are very proud to have the world’s 1st true “drop-in fit” all-aluminum radiator with a built-in oil cooler for the ZN6/ZC6 platform. This new model works with all OEM components, including the fan shroud, AC condenser, and mounting brackets. It requires no modifications or trimming to install.

Speed Academy utilizes the CSF O-line radiator for their project STI!

This new model will be available at the end of 2015 or 1st part of 2016. Contact Jackson Racing for pricing, availability, and ordering details for this highly anticipated cooling solution for the Scion FR-S and Subaru BRZ. CSF #7050O.

Got an idea or a need for another application for our “O” Series? Let us know in the comments!

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    Hello Adlan,

    Yes, the build in oil cooler could be used as an ATF cooler. It is rated for the high enough pressure.

    Hello Z,

    To our knowledge this does not fit the 2023 Subaru Ascent or the 2022 Outback XT. There is a good chance it will fit the Crosstrek but we have not tested it. Dimensionally it should fit but we have not tested it or test the sandwich plate on the 2014 Crosstrek.

    Hi Franz,
    The 3076O should fit normally in your STI spec C Type RA-R. The cooling system mounting points are not different than the standard STI from the limited information I can find about the car. I would advise calling a dealership with your VIN and checking the OEM PN. If it is 45111FE000 or 45119FE000, then it will fit just fine.

    Is there any plan to make the “O” series available for the 2015+ wrx? I’m currently looking for an upgrade in radiator and need an oil cooler as well. My current build is at 450whp/387wtq on the stock block. It is also my daily driver and track car. I have been noticing high oil temps and was looking to invest into a oil cooler and radiator. I figured you guys would be the best bet.

    Hi Kevin,
    We are always looking to improve our products. This is not currently in the works for the O-series coolers. However, the #7042O can be made to fit the 2015+ WRX. You simply need to cap off the Turbo Return Pipe on Top Passenger Side End Tank. You can see how we did this with a fitting on the #7094/7095 here:
    Capping off the return fitting on the #7042O will give you the desired result.

    Sorry for the slow response. There is not a specific plug available for it. You can use any properly sized hose cap and hose clamp to close it off. This could be found at any local auto parts store.

    Hello Tyler,

    Yes, this should work fine. You will just need to run custom lines/plumbing to the cooler from the transmission lines.

    Why did you switch to a NON-Thermostatic sandwich plate? I just received my order of the 3076o and realized the Mocal part is non thermostatic.

    The radiator itself is thermostatic therefor having 2 thermostats is unnecessary and cause another point of failure. Furthermore sourcing the Greddy sandwich plate became unavailable

    2020 sti. Im going to buy it, i just want to know if there’s a specific oil line kit recommended as i understand this doesnt come with any.

    Hi Ryan,

    Because of different manifold set-ups. we’ve opted not to include a line kit.
    This will have to be measured and fabricated by yourself or the shop you choose to have install the kit.

    Kindly advise whether the All-aluminum radiators w/ built-in oil cooler CFS #7042O with fit in my 2011 Subaru Forester SH9 (S-Edition)?

    I have a 2007 STI with a closed deck, ported heads and Aviad 2 stage scavenge sump with 9 qts of 15w-40 oil. Power is 500 WHP on E85. I’m running 235 F oil temps in 95 F weather. I already have Koyorad but using stock STI cooler/heater for break in. Before I buy a large external oil cooler that displaces 40k to 62k BTU’s and having to run it in front of my radiator I am curious if this is enough or what BTU equivalent. Basically is this enough for track use?

    Re. CSF #7042O
    Kindly advise following:
    – GReddy thermostatic sandwich plate – size of thread for oil filter;
    – air-to-oil cooler – size of female thread of radiator.

    Is the oil cooler thermostat setting between 75 ~ 82 +/- 2 deg Celcius, and if so can a 115 deg C or so thermostat be installed instead?

    What a great addition your tank would make to the E36 and E46 M3 world, who use both a radiator and oil cooler for the S54 engines. A common radiator and oil cooler would be a weight savings for racers and much simpler to mount. So when can we have a “o” series E36 and E46 radiator?

    Can you provide information for fitment with expansion tanks? Does the OEM expansion tank for a 2013 sti need to be relocated? Have you done a fitment test with the killer b dual washer coolant reservoir?

    sc300 would be a fantastic seller! Just a note it would be straight forward enough to offer the same design to fit the gs300 also by adding a second set of fan mounting points. using sc300 hoses.
    I have both chassis available for R&D

    Would definetly be intreseted in something like this for the 370z. Email me if you guys need a car for R&D. If not I’m still very likely to purchase if something like this is released for the 370z.