I use synthetic oil that meet the "official" requirement specs for my engine (according to VW). I also use OEM filters. These combined with my driving habits (90% country) allow me to change oil every 10k. (kilometers
)
0W40 for Winter
5W40 for Summer
As for transmission, I hadn't had my car long enough to change it (previous owner did it before I bought the car 10 months ago). Plus I have a manual so it lasts longer.