I have this small oil-in compressor that I use for small tools, tire inflation, etc. I got a real deal on it------for a reason. Since I bought it 5 years ago, it's a great summertime compressor, but has never started without preheating in my unheated garage, in the winter. Last summer, looking for things to do (now retired), I decided to service the compressor. One major item was to drain the original oil and replace it with nice clean oil. Since all I had was some synthetic (Mobil 1) that I had for the mower, I used that. It will now start right up in any temperature and has become a truly useful tool......all because of the right oil. Synthetic is definitely the way to go in anything that uses a lubricant.