What rod do you use to get the best penetration ( sounds like a good joke set-up don't it?) I was thinking of a universal rod like 6011 or 6013 3/32.

if im not mistaken 6011 would be the best because it penetrates through rust and dirt and is a high penetrating fast freezing rod
on the other hand 6013 is a low penetration rod that does not resist dirt or rust at all and was originally developed for highspeed sheetmetal welding