Why is the oil mixing with the water on my astra cdti 54 reg ?

oil cooler

cdc
December 2012

Oil in water, would indicate a blown gasket somewhere. But where? Which gasket. Difficult to know, some more likely than others, bigish job.
As you are not capable, get it to a garage, get it sorted, sooner the better, You are loosing oil, contaminating the cooling fluid, needs to be seen to. ASAP

SD
December 2012