Some say you don't have to drain it all, you just let whatever pours out pour out when you're changing it and then top it back off and bleed. I drained it as best I could though. If you need a thermostat I have one... Was working perfectly and actually replaced a few years back but I cahnged it again cause I did the fan delete mod so you have to put in a lower temperature one.
1998 BMW 328is - summer
1993 BMW 525i - daily
1994 BMW 325i - sold
1992 BMW 325i - gone
1988 Mercedes Benz 190E 2.3-8V - sold