Someone told me oxycontin is one of the most harmful drugs to take,quality worse than black tar heroin?

My friend is a black addict,
he says (??) "Black is a more pure, cleaner and cheaper high,oxycontin has so many added chemicals that its the worst pill you can take and its completely dangerous,compared to black tar heroin"

now im not saying i beleive him. I know Black tar is not a multivitamin compared to Oxycontin.
Could anyone shed some light on the topic?
Thank you all for your answers,I greatly appreciate it.

: http://alcoholdrugstreatment.info/someone-told-me-oxycontin-is-one-of-the-most-harmful-drugs-to-takequality-worse-than-black-tar-heroin