Mine did live with my Oscar for a year, but i know the plecos defence system can pose a threath when swallowed by an oscar.
Once swallowed a pleco will extend all his spines, and lock them.
Mind you, both fish in the picture did not survive, not even after removing the pleco, for the O couldn't close his mouth after the incedent.
Given a good cave , what every pleco should have, the Oscar may not even be interrested, but i didn't want to take any risk to find something like above.
Any pleco above 8 " is fine for me.