Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Original Unit and Its Replacement Leaked Oil

I thought this would be a great product, but the first unit I received never stopped giving off the ozone-like smell that all these radiators emit in the beginning. So, I got a replacement (thank you, Amazon, for making that easy). Sadly, the replacement had most of the same problem. If I ran the heater constantly, the ozone-smell would eventually diminish. However, if I let it sit for a couple days and then turned it on, the ozone-smell would be back, bad as ever. This made me think that there was some small leak of oil in both units. I had to return the second one, as well.