"Old" being 18 months and "New" being recent. I had noticed that my YH was filling my tanks a little bit slower so I decided to disassemble it and have a look. I really dodged a bullet as my cylinder head was just starting to cave in. While waiting for parts to arrive from China, I decided to order a second YH from ebay so there would be no down-time waiting for the unit too cool every 20 minutes, I would alternate between two. I often read stories here about peoples compressors that don't reflect my experiences and I just chalk it up to they did something wrong, or out of sequence and that's that. Not exactly. The problem is, that most of us don't have a lot, or any, experience with this stuff and we are all learning on our own. As it turns out, my first YH was a little brute. It filled my tanks very quickly without struggling at all. I, of course, had nothing to compare it to and thought that was normal. Enter YH number two; the exact same model but a different animal right out of the gate. It works, but it works a lot harder to do the same thing. It sounds like it anyways. I used the recommended 46 weight oil with the original unit and maybe that helped it to break-in quicker. On my new one I went right to Royal Purple. Perhaps it is protecting it from wear a bit too well but I couldn't stand the smell of the other stuff. The other big difference is the running temperature, old unit never gets over 55 celsius, new unit 63. It smells hot too. I put a fan blowing on it. It stayed at 61 for the rest of the fill. I am hoping that it eventually breaks in and runs below 60, we'll see. I was wondering if anyone else had similar units that behaved and operated so differently from each other? If this isn't just a break-in issue, I don't see this unit lasting as long as the original. If that is the case I will be moving on to something else, something quiet. I have done the math though, and if I get a year out of it, it is still worth it to me.