Chris,
It is very important that you clean the cooling system and in particular the radiator very well. You cannot have any
oil left in the system after you repair the leak.
Any
oil residue will greatly reduce the cooling capability of the radiator. The
oil will act as a insulator as it will coat the passages and as we know oil transfers heat much slower than water.
I would take the unit out and flush it with perchloroethylene and then with dilute muriatic acid. (Which is a oxymoron as muriatic acid is dilute Hydrochloric acid after all.)
Hope your problem is minor.