Can Oil Pastels be used with Oil Paints?

I suggest using acrylic paint for the base instead of oil. it's far quicker to dry than oil and is cheaper. Oil painters even use acrylic to make a base before applying oil paint. You CAN use oil paint as a base if you wish, just make sure it is fully dry (not just touch-dry) before applying pastel, this could take weeks if not longer, depending on how oily the paint is (more oily means more time taken to dry)