Some manufacturers will provide oil as part of the package, with the saw. It will run out and Stihl is one of the best producers of chainsaw oil on the market. It is a popular brand and easy to source. This a specific oil used to lubricate the chain as its cuts through the wood and not to be confused or replaced with other oils. A 2-stroke chainsaw will need a 2-stroke oil for mixing with the fuel, before putting it into the tank.