I used preformed. Why work any harder then necessary?? And from what I understand, you have to fold the flap over at just the right spot so that you get the "full" use out of your 6oz. But, as I said, I haven't used those, so I am just going on heresay.
Yes, you can use the same bottle for both types of liners.
I think initially, the walmart brand smell more "plasticy"
But once you get past that, and use them a bit more, you don't notice it. Plus, you pay something like $6.00 for 50 liners of Playtex and $5.00 for 100 liners of Walmart brand. You do the math.......AND I am NOT one to use house brands very often....but in this instance I def. do!!
We had one of the "push up" kind, and I threw it away. You can do the same job with your hand and those other kinds of bottles were just a nuisance. When you get the bottle fixed and shook, Put you Milicon in (if you choose) and then take the lid off the nipple and from the bottom, stick your fingers in and push the liner up, pushing the air out of the nipple. That's just our method, when we did it.
And I just heard Cait throw her bottle on the floor, so gotta go!!!