Airsoft Innovations grenade oil is medium viscosity oil which provides a ideal lubrication for Tornado Grenade operating components. Significant life cycle testing has shown that AI supplied grenade lubricant provides optimal consistency and durability for Tornado Grenades. Unfortunately this lubricant does not have an easily sourced substitute. R/C car shock oils were initially tested and found to provide poorer lubrication than this oil. Maintaining your Tornado Grenade with AI grenade oil is easy: drip 2 drops into a grenade piston opening before resetting your valve. Two (2) drops every other fill provides sufficient maintenance for your Tornado Grenade. Do not use other oil to maintain your Tornado grenade as they may have too low a viscosity. AI Grenade oil now comes in an easy-squeeze, super clear bottle with a recloseable cap no loose cap to lose. It is included in every Tornado box, contains 15ml or oz oil, enough for 150 grenade uses. 15ml is enough oil to last for many grenade lubrications at 2 drops every other filling. 15ml provides 150 drops which is good for 75 lubrications which works out to a crazy 150 throws. *Two (2) drops per fill, once every other grenade fill is sufficient maintenance.