Excessive Oil consumption CausesSometimes people will have problems with a nailhead burning oil or smoking; they think they need better valve seals - but the nailhead did not use valve seals until the last year, 1966. The most common causes are either worn rocker arms or the rocker arm shaft is upside down; the rocker oiling holes MUST face down. Either of these problems will flood the top end with oil causing the oil to run down the guides. Buick did have problems with their early nailheads: the first rocker design from 1953 to around 1956 dumped too much oil on the guides, so they moved the oiling hole back closer the shaft. It is also possible to have a PCV system that sucks oil out of your engine and into the intake where it mixes with the fuel as it goes into your cylinders. It is very important that you ALWAYS use a breather with a PCV: anytime the crankcase is not vented properly pressure will build up causing oil leaks and oil consumption.