Can anyone tell me if a small area of missing fins about the area of 6" x 2" at the bottom area of my radiator will effect its performance. Whilst removing the rad to change the timing belt I noticed the fins corroded, however the temperature guage still reads normal. Would it still do its job or should I replace the rad just in case, and if so would a non lexus radiator that I have sourced at approx £120 be adequate.

once one area goes on the fins the rest start to go quite quickly then they fail (personal experience) i found mine doing a coolant change thought it would be ok then it failed 1000 miles later.
Out of interest which mark GS is it as i have mk1 i'm splitting atm and the rads only been in for 6-8k