Yep, always check the radiator level when cold in the radiator as well as the overflow tank.
I picked up a used Subaru some years ago. Overflow was full and full of black oily stuff. Radiator took over a gallon. When I started it with the radiator cap off it looked like Old Faithful.
If the PO didn't know about the issue, I consider the engine junk as them most likely have overheated the main bearings.