First VTM-4 fluid change is at 7,500 miles.
Then, if you follow the normal maintenance schedule, it is at 30,000, 60,000, 90,000, 120,000, etc. miles or every two years.
If you follow the "severe" maintenance schedule, it is 15,000, 30,000, 45,000, 60,000, 75,000, 90,000, 105,000, 120,000, or every 12 months.
There have been some incorrect statements that it's "every 7,500 miles for severe maintenance."
You only need to follow the severe schedule if you drive under the conditions clearly outlined in the manual. Beware that some dealerships, in an attempt to try to increase their service department revenue, will try to talk you into the severe schedule when you don't need it. The key is that the manual says that you have to frequently/mostly drive under some of those conditions. If you only drive occasionally under those conditions, the severe schedule does not apply.