Veterans Deepak Thakur struck a double, while Roshan Minz, Prabhjot Singh and Gagandeep Singh sounded the board once each in Indian Oil's big win over Army who pulled one back through Ansulin Embrom.
In the other semifinal, PNB rode on Damandeep Singh's brace to come back from behind to pip Central Railway 3-2.
PNB were down 0-1 after Nizam Mohammad's third minute goal for Central Railway who made it 2-1 after Affan Yousuf's 14th minute goal.
The final will be held tomorrow.