Engine is GA15de (1.5 litre chain driven camshaft) First symptom was
sudden release of coolant from under the inlet manifold. Haven't got
there yet to see what's gone - but it doesn't seem to be pipes from
radiator to or from or around the pump, but I won't be able to see where
without first removing the manifold. The water has lots (really lots)
of oil in it - but there's no trace of water in the oil. Was running
fine, oil / filters etc changed a couple of weeks ago - and not a hint
of oil in the water then. Car was stopped immediately when the pipe
went. It looks like it may have been blowing back into the header tank
for a few minutes before it blew - there's a bit of oil in there too.
I guess it has to be a head gasket, but before I rip it to pieces, is
there anything else I should consider?

Thanks.