My M3 Project Will Never Run Hot Again Thanks to This Gigantic Oil Cooler

·2 min read
Photo credit: Brian Silvestro
Photo credit: Brian Silvestro

Last summer I picked up an E46-generation BMW M3 with over 280,000 miles on the clock. Though it looked nice on the surface, most of the suspension was shot, while several other items were in desperate need of replacement. I’ve since improved a whole bunch of stuff, and the car drives a lot better than it used to. But one thing was still nagging me: the oil temps.

Anytime I drove this car in warm weather, the oil temperature gauge would read past the middle 210-degree marking. Under normal cruising it would never run hot enough to become an issue, but it still irked me. Even more worrisome, the temps would spike to 250-plus degrees if I made multiple trips to redline. It was the reason I decided to call it quits early during the car’s first autocross. This past weekend I finally installed a solution.

FCP Euro was nice enough to send over one of its track-ready solutions for the E46 M3’s oil cooling problems: A high-performance aluminum oil cooler made by CSF. It can hold twice as much oil as the OEM unit, and bolts right into the car without any additional modifications needed. It’s the go-to upgrade for track rats who push their M3s to the limit, and the easiest solution for my pesky temperature spikes.

Installing the cooler took less than an hour, as there are only two bolts and four mounting tabs that hold it to the bottom side of the radiator bracket. The stock plastic shroud mounted to the factory cooler was way too small to fit this CSF unit, so it had to go. A side-by-side comparison shows just how much beefier the new cooler is versus the old one.

After completing the install and running the car for a bit to make sure there were no leaks, I took the M3 out for a short test drive. I made sure not to keep it leisurely, as I wanted to warm the oil up and allow the engine to rev out. This way I could make sure the cooler was doing its job. And it was! Throughout my test drive the oil cooler didn’t rise over the halfway mark once. Mission accomplished.

The only way to know for sure whether this cooler is good enough for track work is to, well, take it to the track. I’ll probably go try another one of Lime Rock Park’s autocross events before going to a real, honest track day. If it performs well there on the autocross course, then it’s off to the track I go. Between those, I want to also get a few more suspension parts replaced. Stay tuned.

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