Yeah, I am with you. Black smoke = too rich fuel mixture. If your valve seals were bad, you would get bluish smoke on startup. If you get bluish smoke on acceleration, it is more than likely rings. Have your exhaust gasses checked. Check the plugs to see if they are oily. If the car is running good, I doubt you will find oil on the plugs, as they do tend to foul out and cause running problems when there is an oil problem.