Well, I jacked up the car, checked for holes etc. Checked the top, nothing. Double checked the oil pan, nothing. I havn't taken the car apart yet, but is it safe to assume it is a blown head gasket? I wiped the area down and started the car, couldn't tell where it came from, just above the oil pan but not in sight from above. I did some searches seems like a common problem among the 420a. Please let me know any other symptoms. Thanks.

You can bet its blown if your losing coolant and can't find where its going to. Also you will find that your oil has some frothy stuff in it. White smoke out your tail pipe is a good indicator as well, and it will smell like burnt coolant.
Do a compression test/leakdown test to tell for sure.

Check ur coolant color/smell. if its dark and murky then more than likely proly oils in it. also if it smells like oil. also u will have high engine temp, and a ton of white smoke coming from ur exhaust... those are the main symptoms

A simple easy test to see if ur oil mixed with coolant (sometimes its hard to tell). All you have to do is pull out ur dipstick and rub the oil on the hot exhaust manifold (car has to be at normal op temp)and if it just smokes then its just oil but if it sizzles with bubbles n shit then u got water/coolant in ur oil.