Aoa. I bought civic exi 2003 few months ago. According to the previous owner all of its maintainence was carried out at honda centre and he was using genuine honda oil (he didn't know which grade). I changed the oil at guard autozone(no honda centre in abbottabad) and put honda genuine oil 10w30. The car reduced oil a little but there was no problem,ride was smooth and it gave good milege. Recently i put honda genuine oil 5w30 from the same shop. After the oil change the car started missing and the fuel average dropped from 12-13km/l to 9-10km/l on long route and 10-11km/l to 6-7km/l in the city. It also started producing black smoke at higher RPM. I got my engine checked and found heavy carbon deposits on the plugs and in the throttle body. Engine oil had turned black. The mechanic suggested to change the oil and put 10w40 or 20w50.
Need ur suggestions plz regarding which engine oil should I use. The car has done 112K overall, and the engine was in good condition before that.
Thanks
