I didn't use it for stretch marks, but i used it for a scar I had after surgery and it was amazing.
You have to apply it quite liberally though (not like half a bottle, but say, a two pound size coin for about 1/3 of your stomach), and do it twice a day or else you won't really see any results. I can't really remember how long it took exactly, but you definitely do see results. Because mine was obviously a deep scar it probably took a number of months with me.
Use Bio-Oil and a tub of 100% natural shea butter. I have a friend whose bust grew really fast (literally, flat to big C in a year) and she swears by it. It took her 6 months or so but the results were worth it. x
I have scars from surgery and i've been using bio oil for about 3 months and they have faded loads. You have to sort of massage it in quite deeply, not just pat it on. It also is clearing up the eczema on my back a bit, really is good stuff, I just wish it was a bit cheaper, I want to use it all over my skin every day haha.
I used it on some scars - it hasn't faded one of them at all but the others aren't really visible anymore. I used it for at least 6 months.. But I wasn't using it 3 times a day, just once (or when I remembered). Haven't tried it on any of my stretchmarks as they don't particularly bother me/aren't very severe.
I used some on stretch marks once a day for about a month and they went away completely. They were those ugly dark purple ones but now they've gone. I only used like three drops for my boobs and hips and that was more than enough.