Diesel has a Cetane rating and Petrol has an Octane rating , never the two should meet . Because Diesel is ignited by the compessed air in the cylinder reaching 500 degrees , Petrol will create detonation in a Diesel engine as it will ignite prematurely as the piston is still travelling upwards and that puts great shock loadings on bearings etc . As it is still running fine you will be OK as long as you drain the tank and refill with Diesel .
