1) have you confirmed it’s not water?
2) what year/model is your car?
If it’s oily/viscous and not water, it can really only be three things:
Coolant (has an obvious blue hue)
Drive unit oil (reddish)
Brake fluid (most likely given your grayish-clear definition).
It’s easy enough to check the level of your brake fluid reservoir by popping off the upper trim panel in the frunk.