Radiator or oil cooler first??

[SuperDave]

Thanks guys. Any recomendations on the oil cooler to get?

Without knowing what engine you are using it is impossible to suggest a size. Also you need to keep in mind that a cooler large enough for the track is way too big for the road. I know because I have one I sized for the track. On the street I have to block air flow to it, and I have a thermostat.

You need to start by knowing what oil temps you reach at the moment. If you aren't going over 120*C then you have nothing to worry about.

A B16/18/K20 for for track use would need something in the 19 row size from Earl's or equivalent. But you will have problems with cold oil even with a thermostat on the street.