Will BS VI fuel destroy BS IV engine? We explain!

The BS VI norms will come into effect from April 1, 2020. This would mean two things: One, automakers would no longer be able to sell vehicles that do not confirm to BS VI norms; Two, oil retailers will stop selling the BS IV fuel and instead roll out the BS VI fuel.

So what happens to all the car and bikes that were engineered to run on BS IV fuel?

First, the good news. If you have petrol engine-based car or bike, don’t worry. There is very little change to chemical constitution of the fuel.

If you have a diesel car or SUV, then change in the fuel composition is significant. The ‘low sulphur diesel’ that you buy currently has 50 PPM [parts per million]. The BS VI diesel will only have 10 PPM of sulphur, which of course is much cleaner and therefore, better for the environment.

Why Sulphur Matters

Sulphur in the fuel helps works as a lubricant for injectors in a diesel engine. Diesel engines have injectors that transform diesel from a liquid state to an atomised spray which then combusts in the cylinder. Some of the fuel is actually allowed to leak to lubricate the injector as it has moving parts. [The fuel is subsequently channelled back to the fuel tank.] If you have a low level of Sulphur in your fuel, it will affect the lubrication inside injectors and damage tem over period of time.

If that happens, the fuel supply to engine will be erratic, the combustion inefficient and all this would result in higher rather than lower emissions. This in fact happen the last time India switched standards and moved to BS IV.

Diesels in Trouble, then?

Not really. The fuel companies say that they are adding alternate lubricants to make up for reduced sulphur content in the BS VI fuel. So, that should take care of the injector wear and tear issues.

What if the BS VI Fuel Rollout Gets Delayed?

While Delhi has switched to BS VI fuel already and it is certain that all of NCR will meet the April 1, 2020 deadline, the whole country may or may not follow suit. Then the question becomes: what happens to BS VI cars if they run on BS IV fuel?

Maruti and Kia say nothing. In fact, Kia says it has tested Seltos for a 100,000 km with BS IV fuel and didn’t see any signs of excessive wear and tear. Interestingly, Kia’s sister firm Hyundai says there will be some wear and tear but only over long periods. For instance, the particulate filter might get clogged or might require change faster if the car runs on BS IV fuel. But we are talking 8,000-10,000 km run here. And once again, this will apply largely to diesel cars.

However, unless both the car and the fuel are BS VI compliant, there will be no gains in emissions. But what about fuel efficiency or power? Well, that another story.