[fixit-p]

I did some research on the sanden compressor and it turns out that it's basically an Axial Piston Pump which I am familiar with in hydraulic applications. On initial start up of the hydraulic version it is a must to fill the case with oil otherwise the pump will fail immediately (the Sanden wont fail as quickly due to the operating pressure on a hydraulic system is much higher) thats because of the way it operates. When the input shaft rotates the cylinder barrel and pistons also turn at the other end of the pistons there are wear shoes connected to the piston rods which rides against a swash plate (on the Sanden the swash plate rotates while the cylinder barrel and pistons are staitionary but the same basic principle of operation) the angle of the swash plate determines the volume. On a hydraulic pump the angle of the swash plate is variable and is controled by system pressure the Sanden has a fixed angle and therfore a fixed displacement. Using an oiler on the suction side of the pump may lubricate the top end but not the critical components in the case. The Sanden does have a plug to fill the case with oil and should be filled at least 1/3 to 1/2 way (imo) because the fixed angle of the swash plate (hydraulic term.) is fixed, the connecting rod between the piston carrier and the cylinder barrel needs to pivot and the Sanden uses a ball and gear setup (to preload the piston carrier to the swash plate) is another high friction area. Also because the pump is a piston pump there is probably going to be some blowby of the compressed air and it is now an open loop the case should be vented to prevent pressurizing the case and blowing the seals. I hope this is helpful.

Ref. http://www.sanden.com/images/SD_Service_Guide_Rev.2.pdf