Regular Woolite detergent can be used on dark clothes and it will clean them pretty good.
However it's best to buy the Woolite Dark Laundry Detergent to use on dark clothes as I find the Woolite Dark much better at cleaning dark clothes.
I have used regular Woolite on my dark clothes and the clothes cleaned just fine but I find that use of Woolite Dark is better at cleaning dark clothes because Woolite Dark is formulated for cleaning dark clothes.
Woolite laundry detergent will work in cold water.
Woolite Laundry Detergent works great in both cold and hot or warm water so you can use the Woolite laundry detergent in all water temperatures and it will clean your clothes just fine in any water temperature.
Also when you're washing new clothes for the first time, wash the new clothes separately because the colors of new clothes can run no matter what laundry detergent and water temperature you use to clean your clothes.
Woolite laundry detergent is liquid so you can use the Woolite laundry detergent in any washing machine as well as when washing any clothes or laundry.
Make sure to use the correct water temperature though to make sure you do not ruin the clothing or laundry.