Get a two core they have some cheap ones on ebay but they are only 1 core, biggest probelm with the non externial oil cooler engines is oil temp, In the mini sprint world they see temps 40-60 degrees higher than the water, and is the general cause of engine failure...In other words, explore the oil cooler option, everytime i raced my gixer 6, the water temp would sore to 240.. the fluid only cools the head, and has a cheesy cooler that goes into the oil pan... c and r make a nice rad but its 300 bux, well spent IMO...