The nation-wide rollout of E20 petrol ( a blend of 20% Ethanol and 80% petrol) has sparked a lot of debates. Not everybody is happy with it. The availability of pure petrol (E0) is limited. However, if you have a CNG car, it is advised to use pure petrol instead of E20. Doing so can protect the vehicle from long-term damage.
The reason lies in the way CNG cars are used. Most owners prefer to run them on CNG most of the time. The petrol in their tanks remains unused for months. Owners keep refilling CNG and continue to use these vehicles. This is where the problem begins.
Ethanol-blended petrol may cause various issues if kept unused in the tank. Ethanol has a hygroscopic nature. If the fuel remains in the tank for long, it aggressively absorbs moisture from around- more precisely, from the air inside the tank. This will then trigger phase separation- a process in which the ethanol will separate from the blended fuel and bind with water to form a separate ethanol-water layer.
This will then settle down at the bottom of the tank and be sucked into the engine. This can cause severe fuel-line damage in the long run. As we have seen in recent cases, fuel pumps can also get damaged, due to strainers getting choked. In non E20 compliant cars, rubber parts will also get damaged by the fuel’s ethanol content. All these can lead to costly repairs.
Due to the above concern, it is often recommended to keep the tank full in petrol cars when using E20 petrol. This will help in reducing the amount of air inside the tank and minimising the chances of phase separation.
People mostly buy CNG vehicles for their cost benefits. Running on CNG helps reduce fuel bills significantly. CNG as a fuel, is cheaper and gives more kilometres per kilogram. Most of the time, owners will prefer to drive in CNG mode. This reduces the use of petrol.
Modern cars are even capable of starting in CNG, which further minimises the dependency on petrol. As a result, petrol is used very rarely and remains stored in the fuel tank for weeks or even months. In a recent video shared on Instagram, the owner of a Victoris CNG says that petrol remains in the tank for around 2 months.
E0 petrol is pure petrol without any ethanol content. Its availability is very limited now. Only Indian Oil Corporation’s XP100 and Hindustan Petroleum’s Power100 are kept completely ethanol-free. These have a higher octane rating as well. This further improves the quality of combustion. The best bet for CNG owners is to use one of these.
These, however, cost much more than E20 petrol. The XP100, for example, costs Rs 167 in Delhi. Rs 65 more than regular petrol. For CNG owners, however, this price difference may not be of much relevance, as refills happen one in a few months. The extra money they spend, will be much less than what possible E20-related repairs could cost in the long run.
E0 petrol being completely Ethanol-free, does not absorb moisture or undergo phase separation. It is much more stable than E20 for long-term storage. For CNG car owners who rarely use petrol, this is a safer option. Many CNG owners have also started following this approach. For example, filling up pure petrol for Rs 2000 once in 2-3 months and paying for CNG for all regular drives, would make sense for most owners. Since petrol usage is low, the higher price per litre does not significantly increase overall running costs.
At first, paying around Rs 167 per litre for premium petrol may seem expensive. However, when you compare it to the cost of repairing or replacing damaged parts like fuel pumps, injectors or tanks, the extra expense becomes justified.