Matt from old V was keen for wire nuts.
For connections which don't need daily un-doing, I really prefer that idea, or
These inexpensive grub screw "euro style" wire joiners are excellent.
Why? The clamping pressure does not depend on spring action.
The screws mash the wire with many hundreds of pounds pressure,
and each time the screws are reset, the wiping action removes any oxide.
For these connectors, the best practice is as follows:
-Tin the wire ends
-Grease the screws and the wire ends lightly with any sort of synthetic or silicone or regular grease; whatever will not -tarnish- the wire.
For this reason, I most prefer silicone grease because it is inert,
without any additives that might possibly make oxide films in time.
"Dielectric" tune-up grease is fine. ALL greases are dielectric, really.
That's the nature of such things, unless they are loaded with graphite
or silver paste.
-Screw firmly enough. Later (
soon),
retighten, because the wire will mash down,
and you restore the pressure this way.
-Eventually, after a few retightenings over time,
the connection remains TIGHT,
and will not require this 'break in' procedure upon future reconnections.
TIN the wire ends, please, for best service.
BTW, Radio Shack's little 20 buck butane soldering torch is great for even big-gauge stranded wire.
I like these connectors for their cheapness and current capacity,
and for the several sizes available; they just aren't so convenient as push-connectors.
However, for high current work, they are trustworthy indefinitely.
---
sidebar tip:
-If for some reason the white color nylon is objectionable,
Rit fabric dye, a week's soaking in strong dye, will put saturated color through-and-through any nylon plastic.
Of course, remove the metal ferrule and screws from the item, because the dye contains salt as its mordant.
After the dying, soak the plastic in clear water for a few days to let the excess color (and salt) bleed out.
The result: Jet black, brillant blue, red, or any color you like for your nylon parts of any nature---
bushings or bolts--all those things which are available in nylon plastic. It dyes because nylon is hygroscopic.
. and a pile of Dual-speed motors to boot ! 
