Oiling problems? thankfully the Nailhead's have very few, they have an excellent oiling system unlike later Buick's with an oil pump in the timing cover. Buick made 5 different oil pumps, the 53-54, the 55-56, the 57-58, the 59-61 and the 62-66. All the Buick oil pumps are very good except the 1957-58 where a vacuum pump was built into the bottom, it was used to replace the double auction fuel/vacuum pump used in the 1956 and earlier to help the vacuum wipers. In 1959 an electric wiper motor replaced the vacuum unit so the oil pump was changed back to only pumping oil again. We try and keep 1959-1961 rebuilt oil pumps on hand so 1957-1958 owners can upgrade. High volume oil pumps are NOT recommended unless your building a racing engine with added bearing clearances.
Most oiling problems are created by the engine builder, leaving out oil galley plugs or replacing the cup plugs with screw in types that go in too deep blocking oil passages. We have the correct galley plugs, they are an odd size, not 5/8 we had them made. We have also seen the front cam bearing put in wrong so all the oil holes do not line up starving lifters and rockers on one side of the block. You can have over oiling problems to rockers too, if the rocker shafts are assembled upside down the oiling holes are up, this floods the top end causing smoke and oil consumption. Worn Rockers and shafts can also do the same thing.
The 1962-66 oil pumps are a good pump and can be rebuilt if not worn too badly but we have seen many where the idler gear shaft has worked its way up and hitting the crank counter weight. To repair this we press the pin out, clean thoroughly and re-install with green loc-tite, peen around hole so the shaft stays down.
Common oil leaks are caused by defective head gaskets, oil leaks out from the block to head passages. Another is the rear main seal, our rubber seals come with instructions but one of the most common problems is pitted seal surfaces, if you are having the crank shaft ground or polished make sure that seal surface is cleaned up or repaired so the seal has a nice smooth and true surface to seal against. If you must use a crank with a less than perfect surface then go with a rope seal.