I have a 2001 Jetta Wolfsburg. I was told the turbo engine has an extended warranty that I believe is for 100,000 miles. when I bought the car the VW dealer said the warranty will only be honored if the oil changes are maintained regularly. My question is can you do the oil changes yourself and show some kind of proof (what would that proof be-receipt?) or do you have to take it somewhere to get the oil change done-VW dealer or gas station? thanks for any help.