Bruce

I recently purchased an oil cooler from a junk yard rx7, I took it to a mechanic to install(he made better lines for car than stock at fair price). So, anyways I thought that it would be a good idea to use the thermostat from previous oil cooler in my car(I know it works as opposed to the thermostat in old oilcooler), he ignored my opinion. What should i do should i insist he puts the old one in, run the one from the junked car, or not worry about it at all? thanks for any help or opinions on the matter!!