All your questions regarding the use of BS6 petrol and BS6 diesel on BS4 cars or use of BS4 petrol and BS4 diesel on BS6 cars have been solved here.
As per the Government’s stricter emission rules, all the vehicles should be BS6 compliant from April 2020. That means you cant buy or a dealer cannot sell a BS4 car after March 31. In better words, no BS4 car can be registered after March 31.
So, what are BS4 and BS6 compliance? It has come into effect, basically, after the rising levels of pollution in the country. To reduce vehicular pollution, all the vehicles are getting cleaner BS6 compliant engines to run with BS6 fuels.
Can I Use BS4 Petrol For BS6 Petrol Car Or BS6 Petrol For BS4 Car?
In compared BS4 Petrol And Diesel Cars with BS6 Petrol And Diesel cars, there are differences. As for the BS6 petrol engines, they are now equipped to treat the pollutants like NoX and PM. With specially design exhaust systems, these pollutants are trapped.
BS6 petrol fuel also has a lesser sulphur content of 10mg/kg instead of 50 mg/kg. This helps in releasing reduced content of carbon dioxide and nitrous oxide in the air. So, technically, BS4 petrol can safely run on BS6 petrol cars and vice versa.
As of now, BS6 petrol is only available in Agra and Delhi NCR. Soon, it will come up in every city, town and state. BS6 norms come in from April 1, so by that time, most of the petrol pumps will be housed with BS6 fuels.
Can I Use BS4 Diesel For BS6 Diesel Car Or BS6 Diesel For BS4 Car?
In the case of diesel engines, the difference is more. Diesel engines have a slightly different mechanism and in their case, they need more sulphur content. For chemical lubrication of the injectors, higher sulphur content makes the process smooth. If there is low sulphur content in the fuel, it could lead to block or slow the injectors in the long run.
The use of BS4 diesel on a BS6 diesel car or vice-a-versa cannot be felt in the short run. However, in the long run, if you are still using a BS6 diesel for a BS4 car or BS4 diesel for a BS6 car, it will increase the maintenance of fuel injectors.
Also, if you are using BS6 diesel on a BS4 car, it will produce more emissions. Because you are using more power to use the injectors as with a BS4 fuel. While diesel cars now take a lot of years and a lot of abuse without any maintenance/servicing, to emit black smoke. In the other case, the smoke could be seen emitted earlier.
The bottom line is that you are safe to go if you have a BS4 or a BS6 petrol car. Both are capable of running on BS4 or BS6 fuel, even for long term. As for diesel cars, if you are not using their related fuel, their life will reduce and the engine will get more abused.