Since your talking stains, I have to throw in my secret for whites. Asprin! They will also get out most stains.
Ever since I found out how much it helps I keep a cheap Dollar Tree bottle near my washer. Not stained and just a tiny bit dingy and 1 should help whiten.
I usually have to throw 3 in when I do my 15 year old son's whites, like socks. He won't wear slippers and the shoes come off when he hits his bedroom. After that he walks all over in them. He tought he had new socks once, because they were so clean. Now he just looks at me and says "asprin again?"
My 5 year old grand daughter walked out in back in her socks and right into a nice fresh pile of chicken poop. After the screams of disgust, her's not mine, I laughed, I sprayed them good and then rubbed in salt and white vinegar. Washed them and then wash one more time with the asprin. No more poop stains.
The salt and vinegar I use for really bad stains and usually add baking soda. I once washed my husband's jeans with my beautiful new red sweater. He ended up with pink jeans. I mean really pink. We were leaving town for 10 days and he had to run out and buy more. When we got back he said I should just throw them all out. Five pairs of new or newish jeans? I never throw them out. Jeans can be recycled, but since he thought I couldn't get them back I had to prove a point. Took doing it over and over about 4 times, but I'd pour vinegar on them, dump on some salt and baking powder and rub them together like crazy. Every time I washed them, more of the pink was gone. The 4th wash he was shocked. Jeans looked great. My husband worked in the OR, rode Harleys, Vietnam Vet (Spec Ops), so not the kind of guy that would wear anything that had even a touch of pink on it. He was so happy to see those jeans and I got bragged about, flowers and taken on a ride out of town for some fun and relaxation with the money that would have bought those new jeans.
I do use Oxyclean. It works OK, but not as good as any of the above.