Preheating will help,,problem is a stick welder had only so many small rods,,,so that means you will be putting in 50 to 60 amps to get the rod to burn properly,,best to use a small .023 wire mig or a Tig welder, where you can lower the heat input ,,,preheating aluminum for a mig is a good idea as it helps the small welder do it's job,,,you can use a propane torch or electric blow dyer that body shops use for decal removal to do that....preheating is a good idea except it is limited in application or situation due to practicality...convienience etc...
Some of those lies people tell about me, are true