Your owners manual gives maintenance intervals .
VW all but demands 10k as an european standard that should be adhered to .
3k - 4K intervals are 1940s technology , and are used to get you in the shop more often ! Its a sales thing .
7k miles is a good idea for the harshest conditions using non synthetics .
Truth is most standard , good grade oil can go 10 - 15k miles in the best conditions , but should be monitored closely over 10k .
Most synthetics can go 15k , under normal driving conditions .
I fully agree about the stock filter arraignment , and a 10k change interval would be a good idea , with a 20k drain interval . I bought a Datsun truck from an Amoco engineer , with 100k on it , and he had done just this with Amsoil . I continued the practice for another 150k miles before I sold the truck , and the engine stayed clean , with on lubrication troubles at all . 250k miles is a good test !
Besides now having a TDI Jetta , I also have A D'max in an '02 crew p/u , I have used Amsoil from the first oil change , and since 30k , have installed a bypass oil filter system and have not drained the oil for over 30k miles . Thats 30k miles on the same oil !
I do have the oil lab tested every other filter change , which is at 10k the stock type filter gets changed , at 20k both stock type and bypass micro filter get change and an oil sample taken . And this truck is used pretty harshly pulling heavy loads over Afton mountain , which is a good test on anything .
Even if you don't believe in being green , and I hate green ! , the longer you can make the drain intervals without harming you engine or driveline , the better for our planet .
Amsoil will cover proven oil related failures if you follow manufacture intervals , their's or VWs .
Just my 2 cents , your milage may vary , let your conscience be your guide !