I have a liebert unit with 2 O6D compressors. Both units are charged to manu specs, and use the same condensor and evap coil. On the top compressor, when I look in the oil glass, I see the oil being kind of sprayed on the glass. When I look at the bottom compressor glass, I don't see the oil being splattered on the window. What I do see is some small bubbles swirling in the oil, and eventually the oil foams on top.

Both of these compressors are original, and manued on the same day according to the stickers. I am just curious why there is a difference in how the oil appears in the window. thanks