well that all depend on how heavy the load is, how fast you drive, how many pit stops you make etc. alot of stop and go will hose you to.
Does your radiator have 2 extra lines going to it? other than the upper and lower radiator hoses, if there are to steel lines connected to the passenger side of the radiator, then your rad. has one built in. even the small stock one that I had, had the built in cooler.