Head gasket might be blown

If it is making oil it is either fuel or coolant. Most likely coolant at the rate it made the oil. Head gasket issues are common with Subaru.

At the age of your car it is probably due for new head gaskets. Engine oil and coolant make a strange looking gooey brown to yellow mixture that does not look like oil. If you have new head gaskets installed have an experienced mechanic do it and use multi-layer head gaskets like the 5-star brand. It is best to pull the engine to do it right and while you are at it, have the timing belt and water pump replaced.

Hang on...! Maybe you're wrench overflled the crankcase so badly that it's foaming...which can look weird. Before you get all freaked out drain and refill the crankcase with 4.5 qts oil (ignore the filter), and check operation. If you don't overheat your HGs are probably fine. If not, it's far more important to send the heads out for pressure testing and flattening than to change the water pump, if funds are tight. Frankly, in the salt belt a 2001 is much too old to warrant this level of investment. Check for unibody corrosion carefully before putting $1,5+k into it.