Despite oil on the aperture blades, I don't see any sign of haze on the 90mm Elgeet that came with my Solar 57, and I think it is at least forty years old. Unless you keep the enlarger on more than I can imagine, or have a darkroom hot enough to be a health hazard, I doubt the oil will evaporate and condense very fast. And if it does develop a haze, then you can still clean it and the aperture blades as suggested above.