My 2006 Renault Scenic II 1.6 16V is leaking gearbox oil from the Gearbox Breather Pipe on a motorway, but for the short journey and other roads it drives fine. The oil level is correct and I filled the new oil, Castrol GL4 80w90 and nothing has changed. I tried extending the Breather Pipe as per suggestions on other forum, and nothing works. Any help will be appreciated, cant get any solution from the Renault Forums.