Crimping etc

My experience is that there's not a lot of correlation between price and quality. I have three or four tools for insulated crimps, mostly bought on price, but I have one CK branded one which was (a little) more expensive and is by far the worst of them. I think my 'go to' one is one I bought from CPC quite a while ago.

A bigclive test

If you're referring to car wiring - flex rather than solid core mains - get the correct terminals and crimp tool from the likes of Vehicle Wiring Products. I've seen lots of failures on cars due to using those pre-insulated terminals - they are not gas tight and corrode in time. As well as looking a cheap bodge.

interesting...more like Woods metal than solder

They are not new.

I remember Tandy selling "solder with a match" tape in the late 70s.

Fair point, but the work I was doing was around the leisure battery box in the "inside" area, so less potentially exposed than most car wiring. The voltage sensitive relay kit that I fitted (it's Euro 4, no smart alternator) came with some of the cabling, including a "proper" sealed terminal at the main battery connection. My understanding (correct me if I am wrong) is that the pre-insulated terminals are rated for flex as well as solid conduction.

Indeed. I'm guessing that to melt "real" solder properly you would risk burning the heat shrink. Sort of impressive, but I don't think I'll bother to get any.

Fit one using the best crimp tool that exists. Now cut off the insulation and look at the crimp. Compare to one on the OEM car loom.

Probably not. But possibly beyond te range of a heat gun

Get the self-igniting version instead ...

They're sold by respectable companies as well as FaceBook etc ads. ;-)

I've got some and they seem OK - assuming the wire is perfectly clean, which older stuff may not be. But then I'd not have a joint in anything I considered critical.

If I'm putting heat shrink over a soldered joint, I solder it first (with sleeve already on the wire, obvs), then move the sleeve down over the joint and then use the soldering iron to shrink the sleeve.

In the past I've investigated crimped and silver soldered "industrial" terminations by sectioning for metallographic and SEM investigation. I recognise that my recent stuff might not meet OEM standards, but I reckon I can make reliable crimped or soft soldered connections for loas of 4 amp or so in flex rated for 40A.