I have recently bought passo 2007 model, it was my first experience of buying a used vehicle so obviously it didn't went well. I didn't knew how to check engine condition etc. When i bought it, it was giving 11 Km/L Avg, I got the engine oil changed from Panj sarki petrol pump sadar Rawalpindi. Only half litter oil came out of the car, I have used HX 5 oil. Car Km/L average rose upto 17km/L, i was soo happy at that time but it short lived when it started decreasing and stopped at 10 Km/L, now it is giving 13 Km/L. It also gives white smoke at high RPM. I have to get the engine repair or changed, that is where i need suggestion from you guys. I need to know that if i go for engine change can I get the one with eco installed, which came in later models. Secondly after engine change i have to get the new engine number replaced on the documents too, would that be a problem if i would sale the vehicle later in time. Second option is to repair the old engine, a mechanic suggested that he would just change the inner parts of the engine( most probably he was talking about piston or something) with the kabli one so that the engine number would remain the same, he sounded fishy, whats your opinion about this. He is also giving warranty of 10 days. Can you guys also suggest a good mechanic in Islamabad/Rawalpindi area.