Don’t let the title fool you. Unlike every other Q&A I’ve found in my research, this is not a case of an unknown source of oil leaking into the coolant. It’s actually much stupider — I mean, simpler …
Q: If a coolant-related repair had to be redone, and maybe 1/2 of the 1-week-old coolant was caught, but ran over some other parts on the way down so it was slightly darker and obtained a rainbow sheen, and that liquid was strained for solids but otherwise carelessly re-applied, how much trouble is that trace amount of oil likely to cause? In short, is it worth the time and expense (and, risk, in my neighborhood) to empty, flush, and fill again, or is that little bit just not worth the trouble here?
I think this basic Q could apply to all makes/models, but I’m no expert, so in case there are nuances here: 1997 Honda Accord LX with >315K miles and a 4-yr-old rebuilt engine. If the type of repair involved matters, it was replacing a heater hose from the engine block to … wherever that goes. Also, I’m only trying to keep this thing going a few more years, at least until the other car payment is done.