There is almost no restriction on density and clarity of lubricating oil in oil-air lubrication system. Ordinary new oil can be used directly. In general，ISOVG220#—320# extreme pressure gear oil or synthetic oil are recommended to clients.
Quantity of oil consumption for rolling bearing (provided by bearing manufacturer SKF):
It can be calculated using following equation (provided by SKF).
Q = D×B×c
Q= oil consumption per bearing per hour (ml)
D＝bearing outside diameter（mm）
B= bearing width（mm）
C= 0.00003～0.00005（SKF Lubrication coefficient）
oil consumption quantity for gear, especially for open gear：
Q = （D1＋D2）×B÷c
Q= oil consumption per gear per hour(ml)
D1= gear wheel diameter（mm）
D2= pinion diameter（mm）
C＝10000 lubrication coefficient
Q = 30～50ml/m2/h
oil consumption quantity for sliding surface （for example，guide rail plane sliding surface，rimmed cylindrical sliding surface）
The working pressure for the compressed air in oil-air lubrication is around 3-4 bar. Under the condition of many lubricating points, considering a big loss in pressure in many pipelines, operators can increase the working pressure accordingly. Besides，the water content can’t be high, cause it will destroy oil film and harm to other driving devices such as bearing and gear。In oil-air lubrication system，it configures a compressed air treatment unit to deal with filtering, getting rid of water and adjusting pressure.
In oil-air lubrication system, the consumption of compressed air is affected by a variety of factors. Such as, the pressure and the flow speed of compressed air, the structure, size and the sealing types and the tightness of the sealing assemble of the bearing and bearing base. So there isn’t a formula to calculate the consumption of compressed air. According to the practical experience, when it’s used for bearing and sliding surface, the compressed air is supplied successively, the average of compressed air consumption is 1.5Nm3 / h for each lubricating points. When used for gear, wheel flange and track, it uses an oil-air jetted lubrication method, that is, the compressed air and lubricant are supplied together, so the consumption of the compressed air is related to the jetting frequency and jetting time.