QUOTE(voscar @ May 16 2015, 05:34 PM)
can a regular API SN semi-synthetic engine oil last for 1 year with mileage not reaching 8k km? Currently already 9 months but just barely 5k km, i thought to be "green" minded for not wasting it. daily driving but heavy traffic jam at kl area.
a UOA is a sure fire way, but if you don't want to be spending so much, there are other methods (obviously less accurate) as well such as observing (through dip stick or other means) the oil viscosity (not too thick/sticky, or watery), or if your engine is feeling sluggish, or any performance degradation.
personally, i wouldn't be too confident with semi synthetic, as that term is just way too vague. it can be 99% mineral oil group 2 (and below) base stock, and 1% synthetic base stock, or just the additives and they are called semi synthetic.
you'll notice that a lot of API SN fully synthetic EO aren't that much more expensive than semi's, and you can have much better confidence in dragging their OCI out.
as most people had voiced out before especially when it comes to longer OCI: risking the engine is just not worth it.
the engine itself should always be a higher priority.