I have one that is very similar. Any oil in the 30/40wt category designated for compressor use will work unless you are going to fill tanks for breathing air. Mine is 16 months old with about 10 hours run time on it before it broke. Finally found all the things that wore out on it and it basically needs a complete rebuild. Parts are relatively cheap and it is easy to work on but sourcing parts from China takes about a month. I used mine to fill SCBA bottles but if you want it to last I would only use it to fill small bottles or guns. As far as the coolant goes some parts on the inside will rust if some type is inhibitor is not used. If you use water use distilled only. You can use one of the water coolants but you still need a rust inhibitor. I am going to rebuild mine as a back up for my Alkin W31. If I had it to do again I would have bought the Alkin and not have wasted my money on a booster and cheap compressor.