Why specifically use 5w30 when you could just use 0w50 grade engine oil for all cars?

[Thomby]

This thread is really off the rails...not an expert but I will chime in to echo the sentiment that 50 weight is not junk oil, and 30 weight is not fancier nor does it have more additives/modifiers.

Modifiers are used to extend the spread between how an oil flows when cold and its base weight (how it flows at temp), a difficult problem ($$$) with tradeoffs.

A 10w50 would have MORE additives than a 10w30 because you're trying to make it act so much thinner than its base weight when cold.

The original question was not whether to run 50 weight, but whether you could get the best of both worlds by using a heavier base oil (Xw50 might be overkill, but same idea for 40 instead of 30) and dropping the cold number to 0. And the answer was that this wide a spread isn't free, so even though a 0w oil should flow a little better ice cold than a 5w, you have less of your XX base and it won't hold up the same.

So for any future readers of this thread, the best answer would seem to be: pick the base weight that'll protect you at temp (30 most places, 40 for hot locales or track duty), then a cold number low enough to flow reasonably at your winter temps, but no lower (5w for most, maybe 0w in Norway/Canaduh).

 

[rtv900]

So for any future readers of this thread, the best answer would seem to be: pick the base weight that'll protect you at temp (30 most places, 40 for hot locales or track duty), then a cold number low enough to flow reasonably at your winter temps, but no lower (5w for most, maybe 0w in Norway/Canaduh).

my other car just switched it's spec to 0W-40 so that it could be "track and street" oil. When I bought the car it spec'd 5w-30 but said specifically that if you track it you have to change the oil to 10w-40, and then change back when you go back to street. Obviously lots of extra work for people who track and street it.
Last change I got the 0W-40 "supercar" oil (nice marketing term) even though I don't track it just because I got caught up in the new thing.

Bottom line, I'll be going back to 5W-30 on my next change for three main reasons
1) it cost almost double what 5w-30 costs and that engine takes 10 quarts
2) it's not readily available in stores so I had to order it
3) plus even ordering it, it doesn't come in 5 quart containers so I had to get ten individual singles

totally not worthwhile for a street car

 

[GT Elite]

my other car just switched it's spec to 0W-40 so that it could be "track and street" oil. When I bought the car it spec'd 5w-30 but said specifically that if you track it you have to change the oil to 10w-40, and then change back when you go back to street. Obviously lots of extra work for people who track and street it.
Last change I got the 0W-40 "supercar" oil (nice marketing term) even though I don't track it just because I got caught up in the new thing.

Bottom line, I'll be going back to 5W-30 on my next change for three main reasons
1) it cost almost double what 5w-30 costs and that engine takes 10 quarts
2) it's not readily available in stores so I had to order it
3) plus even ordering it, it doesn't come in 5 quart containers so I had to get ten individual singles

totally not worthwhile for a street car

Hmmm….that other car is a C7 Corvette, right? My understanding (based on comments by Mobil 1 representatives at Corvette Corrals) is that the 0W40 was developed due to complaints by Corvette owners having to do oil changes before and after track days.

 

[rtv900]

Hmmm….that other car is a C7 Corvette, right? My understanding (based on comments by Mobil 1 representatives at Corvette Corrals) is that the 0W40 was developed due to complaints by Corvette owners having to do oil changes before and after track days.

correct yes. That's exactly why they did it. So it can work street and track. If I tracked it I'd totally stick with it. But it's basically a $100 oil change with that oil so not worth it at all for a street car

 

[GT Elite]

correct yes. That's exactly why they did it. So it can work street and track. If I tracked it I'd totally stick with it. But it's basically a $100 oil change with that oil so not worth it at all for a street car

Agree about not being worth it. I, like you, just use 5W30 Mobil 1. The other thing is that you need to be careful to not use a European spec oil, as it can be harmful to the engine. Reason being is that European oils have no zinc, as it is banned in Europe (emission reasons). Zinc is used to protect sliding surfaces.

 

[Volfy]

Another thing to keep in mind is that the typical ambient temp range of your locale should weigh heavily in your decision on what oil to use. For me here in the warm Gulf Coast, it is pointless to run 0w-30 or any 0w-XX. Take a look at the viscosity properties of these two oils:

Mobil 1 0W-30
Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 10.5
Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 56.8
Pour Point, °C, ASTM D97 -42

Mobil 1 5W-30
Kinematic Viscosity @ 100 C, mm2/s, ASTM D445 10.8
Kinematic Viscosity @ 40 C, mm2/s, ASTM D445 62.2
Pour Point, °C, ASTM D97 -42

The kinematic viscosity curves are quite close to each other, with the 0w being slightly less viscous at the lower temp range. However, as temp drops below 40C, 0w's viscosity curve will continue to climb higher (thicken). My guess is before reaching 32C, it's kinematic viscosity will already have gone past what 5w-30 is at 40C.

So, my engine running 5w-30 will not see its oil's kinematic viscosity go outside of what a Canadian engine sees running 0w30. In fact, the Canadian engine will experience far higher viscosities at Winter temps down to -40C.

For my cars that we do AutoX/track, I run 5w40 year around, because the motorsport season is year around. I'd rather have that bit of extra protection on the high temp range. The times I ran full-on track days with four 20-25min sessions in August/September, I actually did switch to 15w50 just for the event. Yeah, it was a bit of a hassle to switch back and forth, but those events were 275-330 miles away near DFW. Adding up travel/hotel expenses and event registration cost, those were easily $500/event, So, a couple of 30-min oil changes ($35 each) were nothing compared to the overall time and $$ spent. Well worth it for even better protection.

For local AutoX and shorter-duration Track Sprints, I just stay with 5w-40.

 

[ElChanclo]

The other thing is that you need to be careful to not use a European spec oil, as it can be harmful to the engine. Reason being is that European oils have no zinc, as it is banned in Europe (emission reasons). Zinc is used to protect sliding surfaces.

****, is that true? All of the big name 5w-40 oils I can find locally are Euro spec; Pennzoil, Quaker, Castrol. I used the Pennzoil for my last track day.
Only the Motomaster 5w40 excludes mention of "Euro" I just don't trust the brand...

 

[7Andrei7]

****, is that true? All of the big name 5w-40 oils I can find locally are Euro spec; Pennzoil, Quaker, Castrol. I used the Pennzoil for my last track day.
Only the Motomaster 5w40 excludes mention of "Euro" I just don't trust the brand...

They just use another aditive instead of zinc. EU oils will be just as good as NA oils. They might be more expensive though.
Also, most new EU cars require low SAPS oils to protect GPFs - gasoline particulate filters (which were fitted to EU Stingers) and catalitic converters.

 

[Volfy]

I wouldn't be afraid to use Euro-spec oils, most - if not all - of which still meet the latest API standards anyway. The much talked about zinc (or ZDDP) has been steadily reduced in motor oil content for all oils, not just euro-spec. It's really only a concern in older cars with flat tappet valves. Engines today are not affected by its absence or reduced qty.

Zinc/ZDDP can be classified as an extreme pressure additive. Those can be important for gearboxes and differentials, which is why gear oil typically have that pungent sulfur smell, as sulfur compounds are also another popular category of EP additives. Motor oils don't have that smell, because EP additives are generally not needed. There is no metal-to-metal contact in an engine lubrication system. If that happens, the bearing mating surfaces will self-destruct in short order, and catastrophic damage is all but certain. A small amount of Zinc or any other EP additive isn't going to save your engine anyway.

The last two oil changes I did were both Mobil 1 Euro Car Formula.

 

[Snicklefritz]

The last two oil changes I did were both Mobil 1 Euro Car Formula.

Is that a full synthetic? KIA uses Mobil full synthetic.

 

[Volfy]

Is that a full synthetic? KIA uses Mobil full synthetic.

https://www.mobil.com/en/lubricants/for-personal-vehicles/our-products/products/mobil-1-fs-0w-40

Kia basically calls for API's latest spec. As of 2020, that is API SP, which most of the Mobil 1 synthetic oils meet.