It might not be a low porosity thing. Actually I think that's typical isn't it? I mean I know the oil will absorb into my hair to a degree but it still looks rather slick and a bit matted when I wake up and take the shower cap off. You're supposed to wash/rinse out deep conditioning treatments with heavy oils I'm sure. (Especially when you use as much oil as I use for a DT.
) It's just that you want your hair to have retained some of the moisture so you leave it in as long as you can then you get rid of the excess. Maybe the GSO did penetrate your hair somewhat only it didn't look like it. Did you notice it being any softer after you low pooed it out? Or maybe your hair is just very healthy in general and didn't need it.