why is my 2002 hyundai accent using oil ??

hello there i recently bought a 2002 hyundai accent and its using oil not leaking and its
not burning it either as there is no blue smoke coming out of the exhaust the spark
plugs are clean as they have that nice colour to them so the oil is not going past the
rings i don't think judging by what my plugs look like ;)
i am using 15/40 viscosity oil and the car has done 248,000 klms on the clockit runns
really well and it never misses a beat its great on fuel i get 780 klms to a full tank of
fuel  so its great in every aspect but im worried about the oil usage ??
where is it going ??
if its not going past the rings ??

and i dont want it blowing up on me either ?? is there any other type of oil that can be
used in this 1.5 litre engine ??
i also use oil stabilizer to help it in the mornings so that it will not wear and tear when i
first start it in the morning

please help thanks fonzi