Done properly, in my book a crimper is an acceptable way to attach two wires. The problem is that the crimped connection can corrode over time since it is a simple contact connection. When crimping, I usually try to use a heat shrink tube to seal everything up tight. Since you have already crimped I'd at least tape over the crimp joint to try to seal out the elements. On critical connections though, soldering is still best.

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LRG
1987 300D Turbo 175K
2006 Toyota Prius, efficent but no soul
1985 300 TDT(130K miles of trouble free motoring)now sold