I've put about a litre of Supergrade oil suitable only for petrol engines in my Turbo Diesel car, I have topped it up with Diesel oil but want to know if it going to casue any damage?
Now adays you can use oil from petrol engines and put in diesil with no lasting damage.If you have a performance car like my supra it can cause the ends to start knocking,but this is because they need fully sinthetic oil.If you find the car has no get up and go when it's cold just have the oil changed.
I agree with Norfolk Boy, its just that Diesel oil is thinner than most petrol oils, I wouldnt really worry but to be on the safe side I would change it anyway.