I don't have an opinion of additives...
Morning,
I know the thinking that the softer the water, no need for further surfactants to clean clothes...wrong. I will never buy that...
Sure, you may one of the ones, that with lightly soiled clothes , only body oils etc, that you don't need a strong detergent...
All is one of my favorite old detergents, but the Sun Formula we have now in Liquids is far from the old All powder that was non-sudsing.
No fan of Liquids here, I suppose any of those will work.
Some on the second level detergents, in powder, will protect that speed queen much longer...Unscented surf, fab, cheer...are all better in my opinion.
As Far as loading, with a speed queen or any top loader, let the thing fill, dump your detergent, add clothes while agitating to get the old time feel for the load it will handle...
An Old Guide was to add clothes, and as long as you could push down easily, and clothes were not to dense...you were OK on the loading...
Now about the dry line loading of the speed queen, not over 2/3rd's to the top will produce the best wash action with the least abrasion of the garments/fabrics.
7 pairs of Slacks, 50 waist, is a plenty load for that washer, if not on the tight side.
Going back to a 30 minute wash cycle, will allow you to do these 3 loads in the time that one of these top loads mentioned above can do.
And without all the color fading, bruising of fabrics, strain on the machine.
Hot water is great, but there is Warm in between the Cold, and Hot thinking...
On your load above, Warm for the Slacks.
If heavy, colorfast dress shirts,...Hot will surprise you, keeps deodorant stains and wring-around-collar in check, and warm will be better than cold if necessary for other dress shirt material.
That last load, hot for sure, but warm is better than old cold.
A machine needs no less than warm most of the times to make detergents work better, and to prevent the accumulation of "Scrunge" in the machine, and from redepositing on clothes.
I can't think of one thing that I want cold for, Tepid Maybe, but not cold.
One of the most important statements in Whirlpool and Maytag books back in the day.
Maytag warned that "no detergent works in water below 75°, and Whirlpool warned of damage to fabrics when wet; ie, that was when most fabric damaged happened, and further it was in the spin cycle...Hence their tightly regulated upper spin speed limits.
Anyway, my advice would be to find a suitable powder for your needs, use warm for most loads if unsure of "hot", and don't overload that queen...clothes need to move freely for best wash action, and longevity...both for them and the machine.
Good Luck, Hope you enjoy your new machine,
as it is one of last simple machines out there...
LaVidaBoem
Post Script:
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Have a Great New Year, and send us a few Pics...