Thanks for the excellent primer, nicki. It's an example of the practical-but-not-overly-technical info available to those who simply want to be better informed.

There will be those who will dispute some of the article and others pointing out that it requires some updating, but it's a great start for initiating dialogue and filling in one's knowledge vacuum.

 

I join Curmudgeon in thanking nicki for an informative item that will interest many of us.

 

...its nick L
and you're welcome

 

There is no dispute here. I've been preaching the above info all along...

 

I just want to clarify one point and that is under the 'why is 10W30 recommended instead of 10W40'. Mineral oils (group I and II) rely on VIs to be multigrade, and the more VIs the greater the potential for the oil to 'shear' under load and wear. Synthetic oil, especially groups IV and V are formulated multi grade so they tend not to shear as much. Synthetic oil may still have VIs, but not as great a quantity as mineral oil.

In hotter climates like Australia, Hyundai's recommendation of 5W30 is really too thin and there is the potential that the oil film on heavily laden bearings (crankshaft, big-end) may break down. The factory fill of 5W30 in my turbo was so thin that when I checked the oil level about an hour after a drive home from work on a 25 degree C day, the oil dribbled off the dipstick like water. That's after the car had sat for an hour after a fairly gentle commute on a not too hot day! So I run Hyundai's alternate specification of 5W40 and I don't have that problem anymore. Because it is Motul grade IV synthetic, this oil doesn't need large quantities of VIs. I will do a used oil analysis to confirm the in service viscosity and the amount of shear.

For my air cooled motorcycle we run 15W50 synthetic, the 50 because the air-cooled engine runs hot and the 15 so we don't have excessive quantites of VIs to shear. So ride gently until the engine warms up, because that oil is thick when cold.

I hope this clarifies things. For most drivers in the US which is more of a cold place, 5W30 ought to be fine. For drivers in hotter places, 5W30 may be marginal. Unfortunately Hyundai's recommended ACEA A5 isn't available in anything other than 5W30 or 0W30, so I run ACEA A3 spec oil instead.

 

^^ I exclusively use 0w-20 with no issues in my NAV.

 

Two points. One is the turbo runs hotter (oil is sprayed against the pistons to reduce piston crown temperatures, which is bound to bump up oil temperature a few degrees). The turbo is quite highly tuned and will run hotter as a matter of course. The second point is that Australia is hot. Today is an average sort of day of about 32 and not a cloud in the sky, but we can and do get into the 40s and still expect our cars to run at speed with airconditioning on, possibly into a hot headwind. I have had cars so hot on cruise that they have stretched their radiator hose clamps and started to loose coolant. On that basis a turbo in summer in Australia really needs 40 grade oil.

0W20 is not a recommended oil for Hyundai Velosters. Manufacturers found that '0W' oils are too thin to build a film at low temps and therefore have moved to 5W as a minimum. In the short-term you won't know if you are scouring your bearings, but you could be. You will only know there is damage when it's too late. You should stick with the recommended grades of oil (either 5W30 or 5W40), for warranty purposes as well as engine life.

 

Very informative, thank you for the post.

 

also here is another good read on basics

FWIW, the manual states 2012 G 1.6 GDI:
Recommendation 5W-20/GF4&SM
API SL, SM or above
ILSAC GF3, GF4 or above
oil pressure at 1k rpm is 100kPa (1.0kg/cm², 14.5psi) or above
oil temperature in oil pan : 110±20°C (230± 36°F)