It goes in place of the radiator cap and you pump it to system pressure and see if it holds. Any mechanic or radiator shop should have one. I wouldn't buy one just to do a test. Maybe a auto parts store can loan you one if you want to do it yourself.

 

oil analysis came back okay. No excess fuel and there was silcon they think from the BG additive and mobil oil. I am going to send in another sample after 1000 miles.