Its not just you, I promise. I hate Lead-Free.
PPtk
Did you mean 0.3mm? 3mm is rather large for electronics.
And I agree, I do not like Leadfree solder, unless it’s silver bearing which can be used a little easier (pricey though). The 99%SN lead free type is terrible without production grade reflow equipment.
I have been using solder wires in different diameters but only up to 1.25mm multicore flux wire. For pipe or sheet metal soldering one must get a solder wire or stick without flux I guess, am I right?
I have a corrosive liquid flux I can’t understand how I really should use, but that I had in a kit. I guess this is the type of flux used on bigger metal pieces. And for bigger pieces people use blow torches. May I ask how do you solder using a torch?
I finally got to test out Graves 190 proof grain alcohol on a couple of solder joints. It works great!! A special thanks to PilotPTK for the recommendation 
P.S. I'm going to try my hardest not to drink too much of it 
I was thinking about marketing the stuff.
You’re right - it is 1.3mm. I don’t know what my fingers were thinking.
no wonder I hate soldering, I’ve been using 12 year old flux and lead free solder.
I can only find Kester Sn63 in $20+ rolls on eBay. are there any cheaper recommendations?
Ive been using lead free 99% tin solder for years, and it therefore a higher temperature solder. With sufficient temperature it solders fine, but I find that my soldering iron tips die relatively quickly due to the higher temperatures needed. Ive been using my normal solder more recently and coming back from the lead free this stuff is easier to use.
Im currently using 0.5mm solder, (DickSmith branded) that was bought like 10 years ago. Although I have 1mm solder, I just use my 0.5mm for everything. Last things I soldered were battery connectors for my helicopter, 8Gauge wire and 5.5mm bullet connectors. Had to feed in about an arms length of solder for each connector!
Its all about having Sufficient heat. A weaker soldering iron at a lower temperature means you end up heating up your components more than you should. All soldering irons are hotter than the component is designed for, but the hotter the iron, the quicker you can solder, the lower the actual amount of heat energy that makes it to the component if you can solder well within a second or two.
That said, it does take me a bit longer to do these big connectors, but I pre-tin the wires, connection and then heat up the two together and hold it there still for about 15 seconds waiting for it to cool down and solidify.
I have a cheap box of flux from DX from years ago, and this one is solid at room temperature. works fine though as all I do is poke the wire I’m soldering into this waxy material, especially after warming up the wire, or if I need to apply it, I use whatever implement I have on my table, usually a small screwdriver or something pointy.
Can you hear the difference?