soldering iron
That is actually a pretty fair choice for most automotive work.
You have to consider, with irons, that the tip size plays a big part. Over and above the wattage, the tip acts as a buffer. This 40W iron will probably be better than the smaller Weller transformer gun.
Speaking of transformer guns, it is VERY important to loosen/ tighten the tip nuts "just about" every session. The seem to corrode or work loose, and this simple step seems to solve about 90% of gun problems
Also, "in a pinch" if you ruin a tip, you can just make one --- bend one up out of a scrap of no 10 or 12 solid copper wire. "Everybody" has some scrap Romex layin' aroun', right?
