First off, you do not want to refridgerate or the worms will not gutload. Keep them out at room temp.
I am on "version 3" of my mealworm farm and have finally found what works well for me. I have read many others with their own way - the key is to go with what works for you and your leos.
I use bran, not oatmeal. Both are good, but I find the mealworms are much more active and can move more easily with bran. Bran has a higher protein content than oatmeal, and it is also much much cheaper. You can find it at feed stores.
I also found adding a bottle of sandfire superfoods cricket diet really helps to make them wiggly and healthy. This mix has bee pollen, kelp, alfalfa, and more that really help gut load the worms.
Be sure to add fruit and veggies AT LEAST every other day. I found if you forget, the worms and beetles go inactive real quick. I use apples, carrots, and potatoes. If i find it in the food cart, i also feed greens, yams, or other veggies.
I have also spoken to some who have several bins to seperate stages of the worms, but found with regular work you can have one bin with healthy worms in all stages. Good luck.
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livXpreshun 
1.1 High Yellow Leopard Geckos "Halo & Storm" [seperate cages]
0.1 Patternless Female Leopard Gecko "Wave"
"It takes a certain maturity of mind to accept that nature works as steadily in rust as in rose petals." - Esther Warner Dendel