that is a very idiotic tip... it will ruin the cars engine in the long run...
at op.. i work at atlas engineering, we market the allwin brand.. and used to supply toyota oem parts for cuore... copper radiators were used in manual cuore whereas the auto cuore had a denso japan aluminum radiator...
my opinion get a aluminum radiator... do a full flush of cooling system with mild acid before installing new radiator... ensure that both thermostat valve and switch are working properly... if not then replace.
also radiators such as yours can be repaired.. why not try that first...?