Beautiful but useless. [SEP] The clip is very nice, good quality and looks really good in my car.  However, the oils that I have dropped in there, and I have used 4 different types so far, do not really smell up the car.  I have it on my air vent and I truly expected at least something.  But nothing at all.  I was thinking that it was because i am not running the heater, but it is summer.  who the heck runs the heat this time of year?  On the last hot day we had i was looking forward to getting into my car after a long day at work and smelling the essential oils I dropped into the unit that morning, but still nothing.  Is there a particular type of oil i need to use?  So far I am not impressed with it as an oil diffuser.  It is gorgeous, but does not do its primary function as far as i can tell.  Would someone be able to advise me on which brand of oils they use to make this work right and make my car smell good?