Oil consumption in passat
 

My daughter's 07 Passat uses @ 1 quart of oil every 1500 miles, my other daughter's 09 Tiguan (same motor I think 2.0 l Turbo) uses none. We have been using Mobil 1 synthetic recently, should we go back to VW's synthetic or no difference? I don't know if this is within "spec" for these cars. She drives mostly on the freeway 120 miles, 3x/week.
Car has 59,000 miles on it
Thanks