Well I've combed these forums and read all the comments I can find about leaking and have come to the conclusion no one really knows. Here's my story, and it's not unique, basically I have read the same problem but not a definitive answer - or should I say one that really answers the question.
I have 3 tanks: TFV4, TFV4 mini, Freemax Starre Pro. I normally have each filled with a different juice and carry all three to work, changing tanks throughout the day. I started vaping in October after smoking for close to 50 years, so I'm not a youngster and am pretty savvy about tearing things apart and repairing them, so, please, no "did you turn the Starre top cap to VAPE?" or "did you tighten/over tighten the coil?"
Basically after cleaning, new (or cleaned, dry) coils and filled, tanks are set aside for morning. Get up, get ready for work and, hmmm - the Starre has dumped all the juice, or, pick a different day and insert a different tank. They have all, at one time or another, dumped a full tank of juice. It doesn't happen every day or every time I clean them. The Starre dumped Saturday night, the mini dumped last night. The big TFV4 ha sn't for a couple of weeks - no pattern, no reason.
I use 60 - max juices, authentic coils (as far as I can tell) and am meticulous about checking O rings, dirt, fit - everything.
I don't live at high/low elevation. It's not freezing/sweltering in my home/car/work. I don't drop the tanks, lay them on their side or turn them upside down. I don't screw the top cap on the Starre on really fast. I prime the coils with 6-8 drops and they sit for hours.
I am at a loss - I love vaping but this HAS to stop or I might go back to Marlboros, seriously, and I've been off nicotine since October 1!
I stopped in 2 vape shops today begging for help. The only possible explanation was I have been cleaning my coils by rinsing in water, soaking in vodka, and letting them dry for several days before reusing them. The problem is I can't confirm used coils with leaking. Plus there are about 1000 "How To Clean Your Coil" videos on YouTube and I assumed they weren't all asshats and knew what they were advising people to do.
That's all I've got, sorry for the length but thought I'd get as much info out in this post.