If you test it yourself, remove the sheathing after joining and evaluate the penetration and integrity of the solder bond…
EDIT: I see some type faster than me……
That is the part that keeps me from trying these.
I want to be able to see that I have a good solder joint before covering with (double wall) shrink tubing. If the wire isn’t perfectly clean (rare in an auto repair splice) before soldering, it can be as bad as twisting the ends together and hoping.
The low melt temperature solder is a concern too because if you can melt the solder with a heat gun (and I don’t think they’re thinking a re-work station) and not melt the insulation then you could fail the solder joint at under hood temperatures without expecting it. That won’t happen with normal 60/40 solder.
I wouldn’t use it near an airplane for sure, especially anything from Amazon! I doubt that it could be signed off as a repair with approved materials. Aircraft repair/certification rules are quite limiting, if it doesn’t say you can do it, you can’t.
BTW, Digikey is a very good place to find high quality and consistent material at a good price. Usually the material will be specified to conform to military standards (MS).
D