In 1998 he became world champion with the Netherlands men's team at the 1998 Men's Hockey World Cup in Utrecht. Then Oltmans moved to football. Until 2002, Oltmans served as technical director of football for NAC. Oltmans was appointed coach of the national team of Pakistan during the Olympic Games in Athens and held the position until the end of 2004. In 2005, he returned as coach of the Dutch national men's team. He held this position until the 2008 Summer Olympics. He was the head coach of the Malaysia men's national hockey team until July 2020 when he resigned. He then was hired as the new head coach of Kampong first men's team.