Mineral oil as lube?

Yes it is OK to use mineral oil as lube. You should take care when using vegetable oils and water-based lubricants as they can go rancid and can provide a medium for bacterial growth. Bacteria can grow in water and vegetable oils, but they cannot grow in mineral oil. The emphasis is on proper personal hygiene. With good hygiene, the use of a petroleum based lubricant is not just safe, but healthy as well.

At 14 or 15 it's normal to masturbate. I think your smarter the having intercourse and having babies at that age. This is a problem though as you said you don't want them too know. I know it's embarrassing but kids have to learn too talk to parents about anything and parents need to have these uncomfortable conversations so they are comfortable to have other more serious conversations with you. Masturbation seems little compared to the things kids are going through and not talking about. Drugs and so forth. I think this young female was smart to ask this question because it's why i even read it. I'm much older and needed to know the same thing. Good job for getting answers first but remember nobody cares more about your health then mom and dad!