I start most of my seeds by planting them in flats or seed trays in the fall / early winter and exposing them them to the winter. Some years I am very successful, in others I get poor results. I think I can track the poor results to a late cold snap that kills the seedlings just after they germinate during one of our February warm spells. I am now keeping the flats in the greenhouse to avoid the hard freezes and planting the sees later in the winter so they get enough stratification time and germination as things warm up.
I have not had good results with stratification in the refrigerator due to mold, but now have some white-bark pine that needs 120 days in there for planting on 1 May. However, I believe that they prefer artificial stratification in industry due to the better control.
I have used a variety of planting media over the years ranging from commercial potting mixes to an inorganic bonsai soil. I am planning to use a 50/50 mix of commercial potting mix and 1-3 mm pumice this year. The goal is the strong growth of the organic potting mix and looser mix for easier root spreading when I repot.
It sounds like you may have had a damping off (fungus) issue with your oak seeding. Damping off due to fungus is an issue with seedlings. Commercial growers are careful to use a sterile mix and apply fungicides at the optimal times. I tend to avoid widespread use of fungicides so I have a healthier soil biome. The biggest issue I have with oaks is that the squirrels like to dig up the acorns and remnants so I keep them covered with wire mesh until I transplant in the 2nd year and cut off any bits of acorn.