Temperature consistancy. It takes a lot longer for the temperature to increase. Also, there aren't any hot spots. They said the original system ran at 70-80c (IIRC) which is hot, but that they never had any issues, since it was all that temperature, and it didn't spike up or down in temperature. Adding a radiator and a pump to circulate the oil through it, the temps dropped big time. They have it all on their website that Casper linked to.