Roger’s explanation of modern engines cooling systems is so right. Just look at the radiator problems with the plus six & 4. Whilst the older V8s needed more cooling, just using a fix all aluminium radiator from Mulfab or Simon imho showed a fundamental misunderstanding of what is required. My plastic radiator is hanging on, just, as in very cold weather it just starts to weep at a seam. Luckily so far not once warm or during the summer. I have put off changing it until I can source an aluminium version of the same size. Some quotes I’ve heard of are astronomical in price.