Rubber gloves

Do mechanic work for a few decades without them and your hands will show why.
No one wore gloves most of my time when I was in the business, and after a few decades of solvents, oils and trans fluid my hands started to chemical burn almost every day.
Not to mention what those chemicals do to your organs and the rest of your body.
That's really me in my avatar.:D

Seriously though, you will even look more professional these days if you wear the gloves.
Back when I was heavy into this stuff wearing rubber gloves was a sissy thing to do.
These days it's the smart thing to do.