Quote Originally Posted by 12vdc View Post

That red RTV i don't trust using in pressurized cooling system, they tend to leak if you don't get the uniform torque/ tightness of the crimp tabs. Same as with oil-pans, not unless the surface is perforated with canal designed for sitting the RTV gasket.
agree with this. Plastic rads are somehow "throw-away" once its service life is reached. It is BEST to replace it rather than repair it. converting an aluminum rad with a plastic tank to a brass top tank will only have galvanic reaction and corrosion in just a matter of time and will give you problems. again. in the most unpleasant time...
but in retrospect, if you took care of your cooling system, your rads will last. have owned different cars over several years and noted that STILL, the BEST coolant is the OEM specific for each brand. and replace it as per manufacturer's recommendation. nothing else....