For the professional that uses the tools every day, the tool should have oil added daily. Just a drop or two a day will assure that the oil keeps the internal components moist and well lubricated. Too much oil can cause some feeding problems due to the pooling of excess oil in air ports and chambers. This will create worse problems in cold weather because the oil will naturally thicken a bit, slowing the reaction of the moving parts. If you suspect that too much oil is in the tool, prop the tool up with the air fitting pointing downward and allow excess oil to drain into an oil pan. This is usually enough to allow the tool to cycle smoothly again. Avoid oiling for a few days when this action has been taken. Keep in mind that too much oil is far better than not enough. Dry tools can cause many malfunctions and can cause component damage.