Not sure how the Fords work but the Ram/Cummins block heateer, heats the coolant not the oil. I picked up a factory cover this year that completely covers the radiators. Without a cover I would just start to get heat when pulling in the driveway. Now when completely closed I get heat within one mile of leaving the plant.
Have you ever changed the thromstat and flushd the cooling system? If not you should. I changed the hoses, belts, coolant and t-stat last year and it help a lot.
Most definitely invest in a factory not after market cover that covers the radiator not the grill.
Don