Like you have said, there are so many variables, it is a very difficult one to start with. I have tried for several weeks searching the internet with every search engine I could find to try and get some idea (or even a range) of the oil temperature. I have not even got close !!!!
The best I have managed is to find an oil expert who has worked with the Honda, Suzuki, Kawasaki and Ducati race teams and can say that generally, motorcycles will run at les than 100 degrees C.
The circumstances are a moderately warm evening with an average size rider and an average size pillion. From what I can gather, they had only travelled about 4 miles before the collision and all of that was in a residential area.
The rider claims that when he collided with the car, it split the offside crank case and the oil sensor valve came out, so the oil would have been ejected from the engine under pressure.
I have carried out a test on the road surface with semi synthetic 10W-40 heated to 105 degree C and it had not effect on the bitumen at all.
So that's where I have got to, but I could really do with knowing the temperature of the oil. It would make life a whole lot easier for me when I am standing up in court giving evidence.