Bad squeal from engine not belt drive .

I've got a loud squeal noise coming from my engine . Thought it may have been the belt drive but disconnected that and the noise is still present .. lent the car to a mate for six months and it was low in oil when it got back. Started it up and it was screaming noise goes when the car heats up but comes and goes
.. very low . Any thoughts as to what it could be would be very appreciated .
Flywheel maybe ?
Stock vx .