Oil in radiaor but no water in oil

Just bought this car last month as I am willing to do the work and needed a cheap dependable ride. Loosing oil too rapidly in fluctuating amounts. It's not ending up on the ground or being burned, it appears to be going into the radiator as there is a good deal of sludge on the top. I initially thought head gasket since the oil pressure is higher than water but it was supposed to have been done recently along with the water pump. Compression seems fine, no white smoke, not overheating, no sludge on oil cap either. I replaced the valve cover and plug tube gaskets as the plugs were a little oily hoping that it was the timing belt issue I've read about. Plugs are dry but didn't help the radiator. Mechanic nonchalantly said on an older car don't worry about it. I have already invested a lot of time restoring the rest of the body, interior and suspension. Is it just a head gasket or should I look for a cracked head/block. How bad is it to drive it like this. The radiator spill canister is full of a ton of milkshake today. What do you think is going on (fingers crossed?)