I hope that is a typo and you mean 100ml to 20 grams not 200 :)
I also do 3 coats (first is 120ml to 20 grams, the others are 100:20), it never seems to fill all the lube grooves for me either, if you fill all the lube grooves, you are using too much at a time. I know it's an appearance thing, i like filled lube grooves too. When i get time to build a mixer for tumbling my cast, i'm going to experiment with a thinner mix but use more of it so it is more liquid to get in all the grooves but leave the correct amount of coating behind when the acetone evaporates.