oolant disappearing...

hi i have a 2001 vectra sri and am having to regularly top up coolant level,there are no obvious leaks so what could be the problem...??????


if its not leaking externally than its probably leaking internally into
the engine meaning either head gasket or intake manifold leaking
is it over heating? does your temperature gauge go up near or at H? something you can do is check your oil on the dipstick look for
a milky residue on there also pull the spark plugs out and look for

signs of coolant on the tips check your resovoir for a stream of
small bubbles in it if you see any of these signs you have an
expensive fix ahead