I might have a little insight into oil drinking... Are you familiar with ketogenic diets?
TL;DR, calories from fat may not turn into fat on your body. For a brief introduction to this idea, this article may help.
www.huffingtonpost.com/dr-mark-hyman/fat-health_b_4343798.htmlKeto diets stress high amounts of natural fat. Thing is though, they're diets that help with weight *loss* and metabolic health.
I don't know much, so I encourage people to do their own research, but here's what I understand: by replacing carb calories with healthy fat calories, your body still gets the energy it needs. However, fats don't trigger an insulin response the way carbs do, and they don't get stored in adipose the same way glucose does. Carbs get digested into glucose, blood glucose triggers an insulin response, insulin tells various cells--including adipose--to absorb glucose. Which is why lots of carbs help you get fat.)
That said, a little more poking around suggests that olive oil boosts insulin sensitivity. So, indulging in some highly uneducated speculation, maybe drinking olive oil helps you get fat because your body is more sensitive to insulin, which means maybe it's better at absorbing glucose? I'm honestly not sure.
Part of the purpose of eating so many healthy fats in a keto diet is to improve metabolic health, like reducing insulin resistance or improving insulin sensitivity (I don't know if those are different, but I've heard it put both ways).
So maybe an important part of a gaining diet is lots of healthy fats, but not because they make you fat.
I'm not doing a keto diet, but I'm swapping out significant amounts of carb calorie for healthy fat calories. I've been consuming 6 tbsb of various oils in my breakfast every morning (roughly 720 calories), and I'm losing weight pretty quickly. I started because I was getting pretty regular blood sugar crashes and episodes of hanger, and I haven't had one episode of feeling low on blood sugar since I changed my diet.
EDIT: To be clear, I'm not going for calorie restriction. I eat when I'm hungry, and I stop when I'm full. I think I'm eating a normal amount of calories, I'm just eating more fats and fewer carbs.