i know the reason you dont run seals on your valves, if the clearance between the valve and the guide is correct you will not lose any oil down the guide, now on the other hand if the valve is lose in the guide you better believe it will suck oil down the guide the same time its sucking a fresh charge of air and fuel into the cylinder, ditto for the exhaust side as their is never vacumn present when the exhaust valve is open, did i match wits with ya george?