By the 1980s, Formosa Plastics was the biggest private-sector company in Taiwan, but Wang pushed for more, seeking to expand further into the upstream reaches of the petrochemicals chain. After ten years of hard-fought battles, the group finally succeeded in establishing the Sixth Naphtha Cracker at Mailiao, Yunlin County in 1994. Wang displayed prodigious energy in the project to reclaim coastal land and build roads needed for the facility.
值得一提的是，1970 年代起為了向石化產業上游發展，王永慶向政府力爭設置輕油裂解廠，履遭最高當局否決，1986 年終於獲得核准，之後又歷經 10 年波折，1994 年「六輕」才在雲林麥寮動工，填海造路、築港興堤的魄力驚人。