If you want to down hill. Use Metal -Core 90/10 gas and pulse spray.

You can weld 16 guage to 1/2 inch with one wire,one gas. .045 Metal- Core Tri Mark Metalloy 71 or Lincoln METALSHIELD MC-6. 90%Ar 10% CO2 and pulse spray in any position. Lincoln and Miller have Programs already in machines. You will absolutly love it. It makes most welders look really good and you are spraying so no penatration worries. Equipment is more expensive but pays off huge.You can Short Arc All positions with 75%Argon 25% CO2. You can also spray in flat, horizontal and vertical down without pulsing. Have a great day.