Ciao Gabriele 
Yes I also like Dixan or our Persil (wich is quite the same thing).
I also like AVA, because it is indeed a good detergent.
Years ago I was using Dash and I liked it especially because of the cleaning and whitening ability but then I've stoped using it because some of my whites turned blue because of too much bluing in it.
Altro che "Piu bianco non si puo!" ma "Piu blu non si puo!"
I was sad because I always liked the italian Dash despite the fact that it has a really strong scent. Our "Slovenian" Ariel is perhaps even more scented.
I didn't know for this trick to expose the stain to the Sun, but it make sense for sure. Thank you! I usualy pretreat with a laundry soap when the stain is still fresh and than again before washing and it usually works. Or like Mark said with some dishwashing liquid. But this load was really a big challenge because every single piece was so dirty. But still, I'm happy with the results.
Ingemar

Yes I also like Dixan or our Persil (wich is quite the same thing).
I also like AVA, because it is indeed a good detergent.
Years ago I was using Dash and I liked it especially because of the cleaning and whitening ability but then I've stoped using it because some of my whites turned blue because of too much bluing in it.
Altro che "Piu bianco non si puo!" ma "Piu blu non si puo!"
I was sad because I always liked the italian Dash despite the fact that it has a really strong scent. Our "Slovenian" Ariel is perhaps even more scented.
I didn't know for this trick to expose the stain to the Sun, but it make sense for sure. Thank you! I usualy pretreat with a laundry soap when the stain is still fresh and than again before washing and it usually works. Or like Mark said with some dishwashing liquid. But this load was really a big challenge because every single piece was so dirty. But still, I'm happy with the results.
Ingemar