25-30 watt should do you.
I only use soldered joints for bullet-connectors, otherwise I use crimps, they grip the insulation, you don't get solder wicking up the wire.
Be sure to use electrical flux-cored solder, never plumbing solder and never-ever use aggressive plumbing flux.
Good man many thanks ..I use 24 SWG flux cored, 60% tin, 40% lead.

I would like to buy a electric soldering iron for car wiring , as you know car wires are all different size so the more powerful the better I think. Can anyone help on what wattage I need ?
If for my vw beetle resto .

Soldering not really suitable for cars as the solder wicks up the wire and a bit of vibration does the rest![]()

That's the one I use, when I was more 'hands on' it would be used for two or three hours a day and last three or four years before it needed a new element, unfortunately the replacement elements cost almost as much as a new iron.I use a 50 watt antex temperature controlled iron, and normally use a 2.3mm bit, but for heavier work I use a 6mm bit. I've had this for nearly 20 years now and its still going strong.
http://www.ebay.co.uk/itm/131605495208
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