[Werner]

Thanks to Dave, Synchro, Wade, etc.!

Right, the risk is too great now to damage the cap screws.

I can hardly read all the posts, because of course this is very tough and cumbersome for me. But the advice to use clear cooler water without additives cannot be dismissed out of hand. This is because radiator antifreeze is a polyethylene glycol, and this PEG sweats easily through the narrowest gaps.

Bottom line: I'll wait and see ...