I have used .5 coils since purchasing the Innokin Coolfire 4. Called in an order for juice with a question that I think was misunderstood (not their fault, as I'm new). Was told the .2 coils would be superior but when I got them, they wouldn't fire unless I took the Coolfire up to 40 W, and still get a funny noise, like a quiet whine when firing. Safe? I am so tired of getting bad info (and spending) from suppliers based on who they have on the phone- normally I vape .5 coils at 3V to 3.4V. I am not into big smoke or vaping as hobby-have just used voltage not watts as I've tried so many times to educate myself but Ohms law just does not click with me- want to do minimum to get to quit analogs and then quit vaping. Long winded question and don't even know if this is the right forum. Please advise. Thanks.