A simple test to tell if valve seals are the source of smoking is does the engine blow blue smoke on start up? If so,oil is running down guides into the combustion chamber. Another trick is to get someone to follow in a vehicle at night while you drive the smoker. Try and find hill or a freeway off ramp and slowly decelerate with the throotlle closed. Generally if the valve seals are leaking you will see blue smoke in the lights of the car following you coming out the pipes in the rear view mirror(s). Rings as a general rule generally cause the engine to blow blue smoke when the throttle is goosed or on heavy acceleration. Hope this helps. Good luck.
