I have a 1990 V8 with 115,000 miles. The timing belt snapped last year, damaging the valves, so I had the heads rebuilt. Ever since then, the car has been burning oil. The shop that did the work cannot identify the problem. The car does not smoke when the engine is cold, only when it is warm. It smokes the most when lifting off the throttle, and idling in traffic. At constant highway rpm, there is no visible smoke. I've pulled all the plugs and they all look identical. Good tan color on the electrode, and a clean, white insulation. ( i.e. I cannot identify a bad cylinder) Could I have a faulty crankcase breather? There is no loss of power, in fact, since the rebuild, the engine seems to run even stronger than ever. I burn about 1 quart of oil for every tank of gas while driving in town, and 1 quart for every 3 tanks of highway driving.