2 years or 32 k, whichever comes first. Only vans that will get close to the max mileage interval are high mileage vans sat on a motorway for most the time. City delivery vans will have service assist light on at less than half that.
My van has a theoretical max service of 30+k, doubt it's ever done over 20 before service light come on.
Agreed though, 20k max, and do some research on the 0/30 oil too.