sifus,my first breakdown need help with part no 1. yesterday I top off my coolant as i got a low coolant warning light. This morning when i drop off my missus at hartamas i hear a hissing sound. I noticed that part no 2 is missing and hot air/coolant is coming from there. Do i just need to replace the vent screw or do i need to replace the entire pipe?what coolant can i use? the one that i put is green color pre mix 50:50 but i heard from the net that says BMW coolant is blue color and is not pre mix. i also saw a a white slugish fluid in the coolant reservoir.is something wrong or its a sign that the coolant is old. should i flush the coolant and replace with new?http://realoem.com/bmw/showparts.do?model=AY72&mospid=47632&btnr=17_0214&hg=17&fg=05