Chile/Argentina

I am planning a roadtrip in July 2008 in Chile and Argentina. The plan is to fly to Santiago, drive south on CH5 to Talca and then take CH115/N145 across the border to Las Lenas for some skiing before heading back across the Andes to Portillo, Chile via N7.

Does anyone know if the route between Talca, Chile and Malargue, Argentina is open in the winter or where I can find that information out? There is a lot on the web about the Santiago - Mendoza route, but not the Talca - Malargue route.

Thanks!