I only use Forte and only after i have bought a car, dont really know how the previous owner has been treating it, so I use it just once for that first service. after that regular oil changes with decent oils is what you need.
^^ i do, its pretty good so far. 5-40 gives better cold start protection. But I change to Mobil 2000 10-40 during summer. used for a long time now, very good stuff in my opinion.