Engine radiator Koyo or OEM BMW

My only recommendation after testing several different radiators is to go with Koyo.

My '09 had the bad number, so I bought a Koyo radiator and spent an afternoon swapping it all. That was ~6-7 years ago.

Koyo radiator is the move, it’s all aluminum, no plastic to worry about, the drain plug is legit and there’s a port to add a coolant temp sensor if you want gauges. It has an extra row for better heat exchange and dissipation my only complaint is there’s no aftermarket specific dual cooling fan set up which I feel would do wonders for cooling the engine bay at idle .

I run a 190 in my Honda v6 swapped Miata with a koyorad and it never overheats even in hot weather

E36 on factory, untouched cooling system replaced earlier this year. Date stamps on the radiator, hoses, thermostat housing all indicated they were never replaced.

I looked at what I bought like 165k and it was KOYO Radiator A1998 for $175 and I'm like 100k miles later and it still looks good. I just wanna change it for preventative maintenance since I'm gonna have my mechanic add the external cooler

I run a Koyo 37mm radiator... and I will hit 200+F under hard driving. Under normal driving, my coolant temps are in between 178-185F.

I just bought a koyo and it's a bit of a learning curve installing it. It took a few hours to burp the system of air but now I'm chasing small leaks. The OEM cap doesn't fit the radiator

I've replaced a radiator on a BMW 2018 3 Series with as little as 22k miles. This particular vehicle was leaking from the side tank of the rad, where the plastic is crimped to the aluminum. Nothing abnormal could be seen, just the crimp failed.

BMW N51 engine, SULEV radiator, these cars came with a sensor that sticks to the side of the radiator for emissions compliance. Can't even get it aftermarket anymore (last time I checked) new radiator without the sensor is like $150, with the sensor is close to $800, and no you cannot use the old sensor, if you try sticking the old sensor to a new radiator it won't recognize it and it will trigger the check engine light.