[auburnf30x]

I'm sure this is probably a ridiculous question, but just to be on the safe side.

I've got a very slow coolant leak in my secondary cooling system (smaller tank for the A/C, intercooler, etc). I traced a lot of it to the cap which I replaced. That helped a lot, but I'm still very slowly loosing coolant to where I have to add a few ounces every thousand miles or so. It's been steady, not increasing. No trace of coolant in oil, so it's an external leak. I cannot locate any trace of it anywhere outside, it's so slow that I think it evaporates pretty quickly.

System has already been pressure tested and came back 100%, but obviously the stuff is going somewhere. I would like to add fluorescein tracing dye to the tank to see if I can come back later with a black light and figure out where exactly it is going. I'll be mixing in 6ccs. I can't think of any reason why this would be a problem, but would like to ask before I do it.

Thank you!

[Billfitz]

Fluorescein is used where an organic compound is required, like in the eyes. I'd use a dye made for use in coolant.

[Orion4]

You should use something along this line of Automotive Coolant Dye. Here's one on Amazon: https://www.amazon.com/Interdynamics...kcom05deals-20