I used Liquin for a while and have recently noticed a painting only a year old starting to yellow. I tried Neo Megilp after some friends recommended it--I love it! It doesn't thin the paint too much and if you like a buttery feel, try the Neo Megilp. Now I have a brand new unopened bottle of Liquin.
Everyone has their favorites and I think each person has to use what works the best for him or her.
Renee Price