Is this a 1.3 engine with a mechanical fuel pump??
Did you check the dipstick?
If not, check the dipstick ASAP!
If you notice that there is MORE oil in the engine than when you first changed it, you have a broken pump diaphragm in the fuel pump! The "extra" oil is actually gasoline that is entering the lubriaction system though the fuel pump and thinning out the oil! Another indication of this condition is mysterious moisture around/dripping from the vent tube on the fuel pump.
Until you replace the pump, you need to stop driving the truck because gasoline-thined oil will turn the engine into a pile of junk in notime.
Been there, done that, bought the new engine.