oh also, the main problem with the sludging, especially if its dropped oil pressure enough to set a light, is it completely starves the engine of oil. so it will wear bearings, cam lobes, and possibly worse.

honestly, dont drive the car, and get it looked at.
and check compression, if compresion is low, the rings are shot.

this really wasnt a very good deal at all. sorry to piss all over it.