Answered my own question - https://www.google.com/search?q=is+sodium+hydroxide+bad+for+aluminum&client=firefox-b-1-d&sxsrf=APq-WBtobWPgr5ZvQ-xePLxa0tX5lsyncQ%3A1643386280295&ei=qBX0YYLMEcTLkPIP35-TiA4&ved=0ahUKEwiCwNz76tT1AhXEJUQIHd_PBOEQ4dUDCA0&uact=5&oq=is+sodium+hydroxide+...
It’s going to end up in the top,of the radiator for the rest of that radiator’s life. No worries. Now, if it were a Saturn,loss of rings would be a concern.
Took her out on her first road trip since getting everything buttoned up. 50 miles of secondary roads where I could start the break in process. Ran flawlessly. Never a CEL or anything to even indicate that all the work had been done. Can't open it up yet of course, but I can tell that it's all there...