I'm not sure what the vaseline is going to do for you. If you buy heatshrink large enough to go over the ring terminal it might be too big to shrink tightly over the wire. Best to put the heat shrink on first then the ring. I always solder my electrial connections that are exposed to the weather.

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Bill Reimels
Now down to one:
1972 300SE 3.5 W109 (Euro delivery)