Another engine oil thread. Castrol Edge/Pennzoil/ Liqui Moly?

[ericold]

Originally Posted by edycol

Ambient temperature is not an issue, per se! This means that if the cooling system is sufficient (which it is on BMW), it is fine.
Altitude is a BIG deal, especially in the summer. The higher you go, the lower the air density is. Think about airplanes. The longest runways in the US are in Denver and Colorado Springs because in the summer, air density is much lower, which affects lift.
Well, the way cooling works is that there is a heat exchange between the radiator and the air. Air molecules take over heat from the radiator and with that, radiator fins cool down and with that fluid. However, if air density is lower, heat exchange is much less efficient.
Up until 3,000ft it is OK, above 3,000ft is when things start to get interesting. Above 10,000ft (a lot of mountain passes in CO are above 10,000ft). There is no heat in Phoenix, etc., that compares to the challenges of cooling an engine on those mountain passes, including winter.
Our local track, HPR, is east of Denver and sits at 5000ft. I have seen tuned cars from TX and AZ that don't have issues there in the summer, just to throw CEL here and go into limp mode.

Another problem is atmospheric pressure. The higher you go, the lower the pressure. However, your internal cooling pressure stays the same. That is how vehicles don't overheat at altitude. The problem is that as outside pressure gets lower, if you have any deficiency in the system, loose hose, or cracked radiator, at altitude, there is a higher probability that the system is going to fail; basically, internal pressure is too much. A good experiment is a bag of chips (Cheetos are best). Take it into car through Eisenhower tunnel or Vail Pass, anywhere above 10,000ft and bag will burt. If your hoses or coolant reservoir is wek, well, that becomes that bag.

so when that happens in such a high altitude we need a higher grade viscosity oil,a higher hths or the opposite? i mean ,we need to stay at our normal viscosity oil or we need to choose a different one if doing such commute for a mix use? how it affects the selection of grade-viscosity oil?

some colleagues made of fun of me when i transferred our conversation to them.i need strong knowledge to pursuade them.

[edycol]

Originally Posted by ericold

so when that happens in such a high altitude we need a higher grade viscosity oil,a higher hths or the opposite? i mean ,we need to stay at our normal viscosity oil or we need to choose a different one if doing such commute for a mix use? how it affects the selection of grade-viscosity oil?

some colleagues made of fun of me when i transferred our conversation to them.i need strong knowledge to pursuade them.

Actually you don’t need higher viscosity. Oil can sustain a lot of heat. I ran Mobil1 0W40 to 300f, some run it to 340. Higher viscosity also means more resistance =more heat.
Best way to tackle cooling issues at high altitude is diluting coolant (I mean that is solution anywhere where cooling is an issue). More distilled water and less coolant concentrate. Some manufacturers (Audi) puts in manual to run 90% distilled water on track in their S/RS models.
I run only 10degree freezing point in summer when tracking my car. Water exchanges heat more efficiently than coolant. You only need enough coolant to lubricate water pump and prevent corrosion. That is it.
Of course, living in mountains or cold climate in winter you need to increase concentration.
As for your colleagues, I will try to find some readings.
Or you can tell them to visit Pikes Peak here, 14.112ft. On my VW i can bump coolant gauge to 3/4 in no time climbing that. If you push it a bit, you must turn on heat to max so you additionally cool off coolant using heater core (I run heat at max on track to cool it off better).
Rangers at the ramp to enter Pikes Peak will tell you to not run AC so you don’t overheat, regardless that in the summer it can be in 40’s up there. But, you simply don’t have air. Your lungs will notice that big time.

[edycol]

Originally Posted by ericold

so when that happens in such a high altitude we need a higher grade viscosity oil,a higher hths or the opposite? i mean ,we need to stay at our normal viscosity oil or we need to choose a different one if doing such commute for a mix use? how it affects the selection of grade-viscosity oil?

some colleagues made of fun of me when i transferred our conversation to them.i need strong knowledge to pursuade them.

https://ntrs.nasa.gov/api/citations/...9930091123.pdf


Your colleagues should research what density altitude is.

[ericold]

appreciate !

.i am just trying to understand if there is an oil thing is involved on the whole situation..bcs. you said :

it depends on the altitude and the place of the moon of what oil you will choose next time on uphill track.
what the moon has to do with oil selection?

[edycol]

Originally Posted by ericold

appreciate !

.i am just trying to understand if there is an oil thing is involved on the whole situation..bcs. you said :

it depends on the altitude and the place of the moon of what oil you will choose next time on uphill track.
what the moon has to do with oil selection?

Lol. I think it is typo.
Can’t remember what I wanted to say.
Track is different. You definitely want 40 grade on track. Just because of HTHS margin. But you don’t want too much as higher HTHS means more resistance and influence performance.
With altitude comes heat, and in that case you want robust HTHS. When I said no need to change to thicker oil bcs. altitude, I meant in regular operations, even if you push car hard. That doesn’t equate to conditions on track.
For regular driving diluting coolant is best way to tackle heat. If I lived in TX for example, I would never run 50:50%, more likely 70:30% in favor of distilled water.
Don’t forget, most new BMW’s have also heat exchanger between coolant and oil. Diluted coolant can carry more heat and release it knto environment through radiator. That means diluted coolant will take more heat ftom oil in heat exchanger, hence name exchanger.