Answer:
I help engines spin and pants stay up
You use me from your head to your toes. The more I work, the thinner I grow. What am I?
I lose my head in the morning and regain back it at night.
Although it sounds like I work on a transportation device I actually work in a restaurant.
Without me everyone would lose their head.
What do you purposefully put lots of in and on your body, but run away from when you encounter it outside?