Scotchloks are fine in cars at low currents/voltages out of the weather on multi stranded automotive wiring which as what they are designed for. In fact under these conditions I can't recall ever having one fail, used outside on a car in a boat or on single strand twin and earth they are a disaster but that's not what they're for.
Cheers, Paul
PS I've always fought shy of buying a proper crimp tool at damn near £100 but there's a company in Leeds selling them for £55. I saw them in an advert in one of those magazines for sad people ( like me ) with Land Rovers

of course I can't find it now at 6:00am but I will later as at that price I think they're worth having.