Mineral oil is liquified petrolatum (Vaseline). Supposedly it coats the hair, weighs it down, makes it greasy, keeps moisture out (making it feel even drier than before!) and clogs the hair follicles hindering hair growth. And it's hard to wash out with moisturizing shampoos.
My detangler--Sofn’free n’ Pretty Olive Oil Detangler Spray--has mineral oil in it (at the end of the ingredient list) and it works great. I use it every day. I'm still going to stay far away from petrolatum, but I'm rethinking the whole 'no mineral oil' thing. Maybe a 'hair grease' with mineral oil near the bottom of the ingredient list won't make my hair feel hard, dry and greasy or stunt my growth if I only use it once or twice a week...
This is Karonica's fault! /images/graemlins/grin.gif