In an article in Contractor Supply K.G. Sims says putting certain things in a nailer is like feeding chocolate to a dog – you just don’t do it if you like that nailer (or dog). Here are some of the forbidden items:
a) Automatic transmission fluid, motor oil, and hydraulic oil. They are lubricants but they’re not made for pneumatic tools and can cause the O-rings to crack and break.
b) Wheel bearing and axle grease. These lubricants are too heavy. White lithium is better.
c) Acetone or antifreeze. People sometimes put these in airlines to keep them from freezing in winter. These materials can damage O-rings and the white plastic parts in the tool. It’s better to use oil with antifreeze additives instead.