Viscosity Grade recommendation for Death Valley

I<3oil said:
It’s a lot more than 50
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122F is 50 degrees in proper units ;)

Thats seriously hot even by Australian standards. Gets that hot routinely way up in the northwest of Australia, but down south here in Tasmania we rarely get over 35 and 30 or so is about as hot as it regularly gets in summer.

Last week I could see snow up on the hill above Hobart...
 
I’d run HPL No VII 5W-30 in those conditions. I wouldn’t go thicker than that, personally, because thinner oil actually transfers heat better.

This selection will resist shear, evap, thermal breakdown, etc. really well.
 
OilUzer said:
I see what you are saying, however most if not all owner's manuals have a ambient temperature / Oil viscosity chart recommending thicker oil in summer time.

I have a same route I take many times and yesterday was 91F and my oil temp was about 12F higher than the same route when ambient temp is 64F. This is based on my records taking the same route and with pretty much same (no) traffic, same speed/rpm, etc.

Each engine is different and it's not a one-to-one correspondence but in my case 27F increase in ambient temperature resulted in 12F increase in oil temperature.

There is a reason there are all these recommended engine oil viscosity / temperature charts!
It is "based on science, not emotions!"
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It’s still the oil temperature during operating conditions that’s going to determine which grade is needed. For example, look at TiGeo’s data when he goes racing. In his case, he saw 280*F temps. Higher ambient temps will slow the rate of oil cooling, but if he’s pushing his engine that hard and the oil is that hot, he’s not going to run a 0w20 even if he’s racing in 15*F ambient temps. It’s still the sustained high-RPM use that would drive the need for a heavier grade.

So, even with a 12* increase in your oil temps, what were they?
 
Geez, I'm running 5w40 in both my eurotrash mobiles even in a Tasmanian winter... I probably should move the Alfa at least over to a 0w30 given its all short trips in a cool climate, but i like the very solid HTHS for the cam over flat bucket tappets and its what the engine was designed for in Europe which is not exactly a hot climate.
 
SubieRubyRoo said:
Ambient doesn’t mean squat. What’s your oil temp running? Considering most engines these days have some sort of temperature regulation and they stay roughly the same as engine coolant temp during normal operation (track use is a different story), the coolant temp is 55-80% more than anything ambient on the entire Earth. Unless you’re doing TT racing through Death Valley, there’s no reason to change grades. Based on science, not emotions.
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This. Everyone wants to be personally exceptional, two deviations above the mean, the toughest critter ever to scurry across the sands of Furnace Creek. If a car has 30% extra cooling capacity over one that tops out at 95'F it'll do fine maintaining thermostat temp of ~200.
 
OilUzer said:
I see what you are saying, however most if not all owner's manuals have a ambient temperature / Oil viscosity chart recommending thicker oil in summer time.
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Show us one from a car marketed in America from the last 15 years. Your car in particular, not something found online. And don't get into "the same engine in Australia" because the question was about Death Valley, CA, USA. ;)
 
eljefino said:
Show us one from a car marketed in America from the last 15 years. Your car in particular, not something found online. And don't get into "the same engine in Australia" because the question was about Death Valley, CA, USA. ;)
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As an Aussie I feel obligated to point out Death Valley is pretty bloody hot. I’ve only ever been through Death Valley in more civilised mid March temperatures, but next time i head back to the US I’m keen to experience it in proper hot. We got well over 40 degrees pretty often in summer in Canberra which is as far north as I’ve lived, but my brother worked on the mines up in Telfer in WA - they got well into the mid 50s which is pretty dangerous if you’re not careful.

That's Death Valley hot, so while I get the idea that ambient is less an issue than actual engine temperature, it’s not much of a stretch to see that when it’s that much harder for the cooling system to reject heat the engine temp goes up.

TLDR - Heat soak is a thing.
 
This time of year we are well into the one teens on a daily basis, and will often hit 120F or more. (Today it's supposed to hit 122F). I use 0W-40 Mobil one in my Toyota Camry that is stickered for 0W-16. The engine runs very quiet.

My 2015 Jeep has a 5.7 HEMI V8, and the oil temp around town isn't much higher this time of year, than it is in the Winter months. (Around 215F). It just gets up there much faster after a "cold" start.

However running 75+ on the highway, or towing anything, it can go up as high as 240F. So thus far I have only run the recommended 5W-20. (Pennzoil Platinum). But after I use up what I have, I'm going to switch it to 5W-40, or 0W-40 as well. My older Ford F-150 gets 10W-40 all year round. I have experienced zero oil related issues.

1720432876235.jpg


1720432952767.jpeg
 
One of the most important things when driving in these very high temperatures is watching tire pressures. If a tire is too under inflated you'll be looking at a blowout in short order. Especially at highway speeds for extended periods of time.

In addition to the already high ambient air temperature, you have a much higher road surface temperature. Add in the added heat generated from excessive sidewall flexing, from a under inflated tire, and it's a recipe for disaster.

Also, the same can be said if your tire pressure is too high. On a day like today, (122F), tire pressure can really increase while driving. And if you have them inflated to max pressure in a cool garage, the pressure can get way over the maximum rated pressure, when it's exposed to the much higher air and road surface temperatures..

This is where having TPMS is really nice. If I drive any distance at highway speeds, I keep the TPMS on the screen as I drive. That way I know at a glance exactly what's going on with the pressure on all 4 tires.
 
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