Normally when people say "keep your wire above 16ga". they mean to use a bigger wire, meaning smaller number.
I find that the system for gauging wires is confusing. Most of the time bigger is better. I say most because you would use 000ga wire to carry a 0.25 amp load, just a waste.
Maybe a 250 amp load, but even then you only need 1 or 0 gauge. I'm using 10ga to carry 150amp and no problems. Alot of people have told me to go up to 4ga. but I don't need it. The voltage at my amps is still 12.5 volts. Seeing as most car batteries charge to about 12.6 - 12.8 this doesn't seem like too much of a loss to me.
The main idea for using larger size wires to carry larger loads is because all, and I mean ALL, conductors have a resistance value. Most of the time this resistance just transfers the electrical energy into heat. Smaller wire will resist large loads more and so create more heat. This can eventually end up with burnt insulation o the wire, or worse yet, turn your car into a really expensive bon fire.
A basic note to keep in mind with wires, If you are not sure, go bigger, it'll cost more, but not more than a new car
