2005 Chrysler Sebring oil

Can be analized in a lab my question is why?

I took my car to have oil change and tune-up when when mechanic turned car on there was a loud knocking noise and it was blowing white smoke. I heard mechanic tell another mechanic that they put the incorrect oil in my car. they put 20w50 when it takes 10w20 therefore I took my car to the dealer and the dealer says I have a blow rod. so. I just was wonder if there was some way I could prove this happen?

The use of a higher viscosity oil would not spin a rod. I personaly use 20W50 in my cars in summer. At 32 deg the oil has property of 20W oil as temp goes up so does viscosity to 50W. So rod bearing was hanging by a thread and on start up after oil was drained possible it spun.