For this, we would suggest you walk into the nearest authorized service centre as they will be the better person to assist you. You can click on the following link to see the details of the nearest service centre and selecting your city accordingly - Service centre
The only difference between the Skoda Octavia top diesel and petrol model is of engine only rest the features and specifications remains the same. The diesel variant comes with a 2.0-litre diesel unit good enough for 143PS and 320Nm mated with either a 6-speed MT or a 6-speed DSG automatic. Whereas, the petrol engine is a 1.4-litre TSI petrol that makes 150PS of power and 250Nm of peak torque and a 1.8-litre TSI petrol with 180PS and 250Nm mated to a 6-speed manual transmission only, while the bigger petrol engine is offered with a 7-speed DSG automatic only.