Hi @gwenj
Yes Daz changing is recent. In an aim to make it suitable for “all” wash loads, they have taken bleaching agents out and it now says “for whites and colours” on the box, so they are trying to sell it as a 1 for all product,
But unfortunately when using just one product for all wash loads, there will always be a trade off somewhere; for example, if you use just a powder with bleach, you’ll get lovely bright whites and a cleaner machine, but colours will fade quicker.. Use just a liquid/gel (or anything that doesn’t contain a bleach), you’ll have vibrant colours for longer, but your whites won’t be as white as they could be.
Daz will do a good enough job, the reason why Daz has always been sold as the “whites” powder is because it contains a good amount of blue whitener (our Grandmothers would have known it as dolly blue whitener), it gives whites a very slight blue hue/bluey-white, so our eyes perceive it as whiter. In terms if better than Ariel, hard to say as a definite, as all products have advantages and disadvantages and what works for one person (clothes, water type, machine type etc) may work better (or not) for another. That’s why you may love one product and a friend may not be keen and vice-versa. But Ariel is a top grade product (it is the premium product from P&G who make it (as well as making Daz, Bold and Fairy and Lenor too)
Yes, you can usually always use less detergent than is stated, sometimes we just don’t need as much as is said on the box, and especially with towels as if you get a detergent build up in the towels from using too much, it will cause them to become stiff and possibly start to smell fusty.
Only thing I would say, is to ensure there is enough detergent used to soften your hard water in the wash, as if the water isn’t softened sufficiently, then you will then get a calcium/mineral build up, not only in the machine , but in your clothing/towels too, which again will cause them to become stiff and scratchy. All good detergents contain water softening agents, so you won’t need anything like calgon etc unless you want to seriously reduce your detergent dose (eg using doses prescribed for soft water areas) you will then need to use a separate water softener.
Sorry that’s really long , but I hope it helps :)