REOB contains various elements and compounds found in recycled engine oil: additives to the original oil and materials accumulating from its circulation in the engine (typically iron and copper).
ɹɪˈɑːb kəntˈeɪnz vˈɛɹiəs ˈɛlɪmənts ænd kˈɑːmpaʊndz fˈaʊnd ɪn ɹᵻsˈaɪkəld ˈɛndʒɪn ˈɔɪl: ˈædᵻtˌɪvz tə ðɪ ɚɹˈɪdʒɪnəl ˈɔɪl ænd mətˈɪɹiəlz ɐkjˈuːmjʊlˌeɪɾɪŋ fɹʌm ɪts sˌɜːkjʊlˈeɪʃən ɪnðɪ ˈɛndʒɪn tˈɪpɪkli ˈaɪɚn ænd kˈɑːpɚ.