Im looking to drain my coolant system and put some new coolant in , could someone please give me a brief 123 of how is best to do this , im not an expert tech but can do stuff ok , what do i need to look out for air leaks etc, its really the best place to drain from really and how much coolant/water mix do i need to put in and is it all filled up from the expansion tank ! silly questions probaby but its getting cold and i think i need to get this done ! Thanks in advance Dan