Excellent point. If using a deep color, have the paint store tint the primer with 40-50 percent concentration of your chosen finish color formula.If the project's not already done, what final color are ya doin'?
A darker primer may be advisable.
Maybe 20 years ago this was true, but, not anymore. I always liked oil on doors (especially metal) for its' hardness and durability. Now, the latexes have caught up and you can basically get that same, hard, durable finish as you once got with oils. Oils take too long to dry and you have to leave your door open to bugs, etc. for a long period of time. Most people I work for paint the sidelights the same color as the door.exterior oil base semigloss paint probley best(side effects has high akline and mildews faster) latex semigloss does not stick as well peel like rubber band