Hyundai I30 1.4 2011 i bought it last year around this time and changed the oil, the oil filter, the air filter, (these are all the changes i made since i got the car).Passed a total of 6000km approx, and when i checked the oil level the level was below the minimum requirement (below the L on the dipstick), is that normal, i use Castrol Edge 5-30W C3. What is the recommended oil that i should use for this type of I-30. Thanks in advance