I don't use a syringe nor condom push. And they don't hold 1oz. An oz is 30ml. They hold 1ml.
I have bought from V4L, Bloog and SmokelessImage and all were great. Good customer service. I use V4L and Volt batteries, all manual, all 78mm which is the normal size and makes 120mm ecig (not shorty, not xl).
I can get about 7 day (at about 2-2.5ml per day) use out of a V4L WOW or Bloog/Volt carto with thin clear juices by keeping the carto damp so it doesn't singe. (I actually vape the KR808D-1 1/2 the time so for me that is 2 weeks running 1/2 that amount of juice through every day). I avoid all juices that drop flavoring sediment (clogs carto, gunks up coil,ruins drag, shortens carto life)
This how I fill - it only looks hard - try once and it is easy, especially with the Bloog/Volt cartos which have nice absorbent stuffing (note - the air channel of Bloog/Volt is narrow and you may not see light through it - that's OK)
---
How I fill a cartomizer (Vapor4Life/Bloog/Volt for KR8 or Boge 510 for 510 which are all soft-cap w/ no inner seals and defined central air channel) (1ml cartos)
I use thin (20% or less VG) liquid or Vapor4Life WOW liquids, preferably clear liquids w/ no sediment
Filling a blank carto - I pop off the soft cap (unbent paperclip carefully in the mouth hole, not catching any wires or stuffing!). I hold some tissue against the threaded end hole (or you could use the carto condom spike to plug the hole). I tilt the carto and slowly drip 18 drops (per ml of carto capacity and these are 1ml cartos) onto the inner wall of the carto so it slides down into the stuffing while I rotate the carto. Then I wait 15 seconds or so then I drip however many more drops the stuffing wants to soak up.
Cleanup: Then I do clean-up. If it is leaking, I clean that up. Then I tilt the open end down into the tissue and puff a couple of times into the threaded end to clear any juice out of the central air channel (I want to see light through there). With the carto still tilted with open end down I gently touch a bit of tissue to the stuffing (otherwise that liquid will be gurgling or spitting in my mouth). (And instead, if I really want to avoid leaks I touch the soft bit of tissue to the stuffing while blowing out the air channel.)
Settle: Then since this was a fresh fill of a blank, I now let it settle. I lay the carto on different sides for 15-20 minutes. Then it should be ready to vape. If you use thicker juices than me, then you may need to let it settle longer.
As I am vaping - if the vapor gets a bit light or a bit dry or tastes bit off or the carto is getting unusually warm, I will take the carto off the battery, open it, add 4-8 drops or whatever it seems to want (I will either hold a bit of tissue against the threaded end hole just in case, or skimp on how many drops I add to make sure I avoid drips if I have no tissue). I check to make sure the threaded end is dry, give it a couple of puffs into the threaded end to make sure the air channel is clear, and continue to vape.
Note - it is easy for me to "open" my main cartos for adding juice because I replace the white end cap with a plastic or delrin drip tip (I get them at LiteCigUSA.net). So I can easily pull that out with my fingers when I add juice and it keeps my lips cool if the carto is hot.
