Quote Originally Posted by yebo View Post
advise naman please. i just recently changed oil on my lancer, from semi-synthetic to fully synthetic. car is 2002 model, only 30000 km on the odo. i pride myself before of having a pretty high km/l mileage, 11+ km/l city and up to 15 km/l highway (on semi-synthetic oil). actually before when i had it on pure mineral oil the mileage was even higher, 12+km/l city and 16+ km/l highway. i did not mind the slight drop in mileage when i switched to semi-synthetic since i was thinking of the added protection the engine will get. but now after changing oil to fully synthetic (shell ultra yata yun) my mileage dropped to only 6km/l city. i have not tested it on the highway yet as i had not had the chance. driving conditions are the same as before, no change in driving habits either. could this be due to the oil?

any comments will be appreciated. thanks.
this is like using a premium gas= higher performance = low mileage.