Can someone please explain to me the relationship between the brakes, power steering, and self leveling suspension? I have a 1989 750iL with self leveling suspension and the "oil reservoir" is used by all three systems. Then the brake fluid master cylinder says use only Dot 4 brake fluid and the oil reservoir says use only Pentosin 7.1. These systems are connected, so do the two different fluids mix? Also I just bought a can of Pentosin 7.1 and it is green and what is in my oil reservoir is dark brown, which looks like power steering fluid to me. Any clarification will be greatly appreciated - thanks.