With toyota, honda and suzuki genuine coolant the trace is very easy to see, it looks like colourful rock formation.
With havoline it looks like black oil staining which mysteriously washes away clean with plain water only.
For engine oils, in Pakistan i used to use talcum powder, (the cheapest type that you buy by weight in plastic bags)
Smack some on the area, use a strong light and see the wetness/dampness.
In usa the dye is available easily and i still use talcum for oil check, use that dye for ac leaks and hydraulic leaks though.