This article presents how important is proper functioning of the oil lubrication systems. Presented the most often used are the following types of the return chambers: a) return chamber with a pipe above the liquid surface, b) return chamber with a pipe under the liquid surface, c) return chamber with a pipe under the liquid surface opened at the top, d) return chamber with a sieve inclined at an angle, e) return chamber with a basket filled with Bialecki rings, f) return chamber with a degassing tray, g) return chamber with a cyclone, h) return chamber with a flat degassing tray with welded angle bars, i) return chamber with an innovative degassing tray—star-shaped. Subsequently, moving to the other factors, there is intention to present (1) the test stand, on which the return chambers’ research studies are carried out, (2) the parameters and the scheme of the test stand, and (3) the description of the measurement tool which function is to use two methods of the measurement of the air in the oil, that is modified trapping method and photographic method.