Traditionally most engines were expected to burn a little oil and adding a quart every 1000 miles was considered normal. As emissions and fuel mileage demands increased throughout the late 20th century the demand for much more efficient engines became paramount. Tightening tolerances helped in both regards to burn fuel more efficiently which then also meant unburned fuel and a bit of oil were less likely to go out the tailpipe. By the turn of the century many engines needed very little oil added in between oil changes.
But those engines were also getting smaller and more complicated with more required of them than ever. To help reduce the load on the engine and produce more power, among other technological advances the tension load on the piston rings was eased on some engines and lower viscosity oils were introduced. The side effect to this though would be oil consumption going back up as more oil escaped passed the rings.
Due to the high tech design of everything from PCV and EGR systems down to the intricate porting of oil passages, the modern engines of today call for very specific oils. This requires the use of synthetic oils that were specifically engineered to meet the designs of each engine builder. Using an unapproved oil that doesn’t meet the spec for your engine can void your drivetrain warranty.
If you own a European manufacturer vehicle then you should be looking for ACEA specifications on your oil. These specs were designed in Europe for the exact lubrication requirements and oil change intervals called out by the vehicle manufacturers. And more precisely you should be searching for ones that meet the vehicle manufacturer spec, for example Mercedes 229.5 or Audi/VW 505.00, that is called out in your owner’s manual.
If you own an American or Japanese manufacturer vehicle then the API/ILSAC specification system should be used. American and Japanese car manufacturers do not normally call out specific approval specs but rather the API code (i.e. SN or CF) along with viscosity (i.e. 5W-20) and type (i.e. conventional, blended, or synthetic).
What happens if you change your oil with an off-the-shelf nonapproved 10W-30 at the local warehouse store? The engine will still start and run probably with no noticeable difference but over the next 5000 miles you may be doing irreparable harm to your engine.That expensive engine is likely better off with the correct oil running an extra few miles than using the wrong oil.
If you change your own oil and filter, always follow the vehicle manufacturer recommendations and make sure to refill to the correct level. As simple as this job is you may want to check for online videos or discussions so you are prepared for any oddities that may happen. Many engines now require an extended time to drain completely and the filter housings may require specific tools. Once you’ve drained the oil and changed the filter refill only partially and check the oil level. After that add a half quart at a time until you get to the correct level.