With petrol and diesel prices climbing steadily and the EV charging network still far from dependable, more and more buyers are turning to CNG cars. The appeal is obvious, lower running costs and a smaller environmental footprint. But owners who already drive one often get stuck on the same question, is it fine to run the car on gas all the time, or should petrol be used from time to time as well. Auto experts have weighed in on exactly this, and understanding the answer starts with knowing what kind of fuel CNG actually is.
Why CNG needs a balance with petrol
CNG is classed as a dry fuel because it does not lubricate an engine the way petrol does. If a car runs purely on CNG for extended stretches, the strain can show up in the fuel pump, the injectors and other engine parts. That is why maintaining a balance between the two fuels is considered essential for engine longevity and smooth performance. Most CNG cars sold today use a bi-fuel setup, meaning they can run on either fuel, and in the majority of these models the cold engine starts on petrol first before switching over to CNG automatically once it warms up.
Ignoring the petrol system can prove costly
According to experts, the parts tied to the petrol system should never be left completely idle. The fuel pump needs a steady supply of petrol to stay cool and lubricated. If the petrol tank sits nearly empty for long periods, the pump can overheat, and repairing that is an expensive job. Petrol injectors face a similar risk, if they go unused for too long they can clog up, which shows up as starting trouble or uneven engine performance.
How much petrol to keep, and when to switch to it
Experts recommend always keeping at least 25 percent fuel in the petrol tank. On top of that, driving around 10 to 15 kilometres on petrol mode once a week helps keep the injectors clean and the whole fuel system healthy. On a long drive, switching to petrol about 500 metres before reaching the destination is advised. It also helps to run the entire drive on petrol at least once a month, since this gives the engine a proper cleanup, makes cold starts easier and extends the engine's life. There is a practical reason too, CNG stations sometimes have long queues or simply run out of gas, and having petrol available acts as a reliable backup in such situations.
CNG's benefits, and its effect on valve seats
CNG's biggest advantages are lower running costs, better mileage and reduced pollution. But its high temperature and dryness can put extra stress on the valve seats. Using petrol occasionally helps offset that effect. In vehicles that come with a factory-fitted CNG kit, manufacturers already design the system keeping this balance in mind.
Bonus tips to keep a CNG car reliable for the long run
Anyone driving a CNG car would benefit from a few extra habits. Always fit CNG-specific spark plugs, keep up with regular servicing, and get the cylinder's hydro test done on schedule. Avoid unauthorised mechanics as well. Sticking to these habits keeps a CNG car not just economical but dependable over the long haul.
