RotaTech answers your questions regarding chainsaw oils.
Is Chainsaw Oil the Same as Regular Oil?
Chainsaw oil is specially formulated with mineral-based additives that provide lubrication and protection against rust and wear, making them more suitable for chainsaw bars than traditional oils used domestically, such as motor or vegetable oils.
The viscosity of chainsaw lubricating oils can vary, but will always allow the oil to stick to the bar during high-speed rotation, rather than other oils that would not stick to the bar at higher speeds, keeping your chainsaw healthy and lubricated for longer. You may even void your chainsaw manufacturer’s warranty by using unapproved chainsaw oil.
Can I Use WD-40 as Chainsaw Oil?
You should not use WD-40 as a chainsaw bar lubricant, as the primary use of WD-40 is as a solvent or to dissolve rust. As a substance, WD-40 is not thick enough to stick to the chain bar during operation, and would not be suitable as a chainsaw lubricant.
See this guide on the best chainsaw oils.