Brake Fluid

Help! my brake light came on recently due to a low fluid level, I've added 12 ounces of Valvoline Brake Fluid Dot 3, Dot 4 in the Brake Fluid reservoir and I think I've added too much. After two days of Drving, I woke up this morning and found a huge amount of Brakefluid underneath the car, my question is, if the reservoir is overfill, does the system purge out the extra fluid, or do you think I have a leak? Despite the lost of fluid, the brake light is not ON, I've checked the reservoir, there is some fluid left in there still. I did check the reservoir to make sure that it was tighten. Please let me know if the system has a purge release valve in case of overfill, also, do I have to use MB brake fluid or can I use a third party?

Neil
94 S500

LEAK, LEAK,LEAK. I've never heard of a self purging brake system, as they are closed loop systems. Like AC.

Do you think using a brakeluid other than MB is responsible for it? or the overfill is somehow responsible for the leak?

Update, I've added brake fluid in the Hydraulic reservoir by mistake, now it is leaking like crazy, so far, their is no malfunction on the hydraulic system in the car.