1) It is very important to run with a minimum amount of air in cooling system for 2 reasons. First, if running permanent coolant, air in system causes an accelerated rusting problem in the block due to a sort of galvanic corrosion reation; there is an air bleed screw to assist in getting to zero air (the 'right' amount). Second, air in system will allow increased temps and possibly hot spot(s) depending on volume.
2) There are only two ways to push out coolant. First is overheating (or at least expansion of improper coolant mix). Second is leakage of compression; could be thru head, head gasket or block. If you get a choice, choose overheating.
\'95 P30 Motorhome 16,500gvwr, 26,500mi<br />New Ipump @ 25k, boost, EGT, homemade remote FSD cooler