Oil Weight and Ambient Temperatures

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I asked this before, but didnt get a straight answer.

Whats the point of running a thicker running weight in extreme heat? We see here that (some) Australians and folks in the Middle East like a 50 or 60 weight oil. Wouldn't the radiator keep oil temperature somewhat in check and prevent any oil related failures? I would also think an oil cooler would be a standard option for vehicles in these regions. We also see engines that spec a much thicker weight in Europe and the other mentioned regions while the identical US version will take a 20 or 30 weight oil. (It has been mentioned here that a European car's severe use yields a thicker oil.. high autobahn speeds for example?)

I don't understand the reason behind any of this. In the US, thin seems to be in while other places are still using a thicker oil.
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Another thing, is revs make pressure. If you want pressure at speed, you've got it, no matter what oil's in there, unless something is seriously wrong.

A little extra flow, a little less bypass, is also something you get, going thinner.
 
I have run all sorts in my car and I settled with 10w30 because it is the best all rounder. Gives good fuel economy, smooth and quiet and I'm not seeing any problems running it in a verging fairly high mileage engine in a hot climate.
80% of Australians with the same car and mileage as me will have 20w50 or thicker in the sump because yes for some reason here it is common place to suddenly use unnecessarily thick oil after 150,000km.
I have run 10w30 for a while now in a wide array of conditions for the reason you mentioned, the cooling system should keep it fairly constant regardless of ambient temps.
All I know is the temp gauge on my car is pretty sensitive, but at FOT the needle sits on the exact same spot whether I'm in 40C/105F summer heat with the aircon blasting or whether I'm driving through the snowy mountains in winter during sub freezing temps.
30 weights seem to serve me well and if your cooling system is effective and up to scratch you'll never have a problem
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H*ll at one point I over heated my car (accessory belt snapped) and drove for about 30 minutes with zero coolant.

I think strict US emission control is why you guys get told to use an xW20 cause the same engines here usually spec 5w30 and people will happily use 5w40/50 in these same engines with no ill effects. 5w20 is quite unpopular here but I see it around
 
Oil temp may or may not coorelate well with coolant temp (and it doesn't for the first while of running; oil takes longer to come up to temp without a heat exchanger). And you'd be surprised at the number of vehicles not fitted with oil coolers.

Shannow was able to significantly drive up his oil temp just driving in a lower gear for example.

Watch this video. This is a car (on the Autobahn) with a 7L sump and a large factory heat exchanger:



It isn't until he is north of 150Mph that the oil temp starts to come up, and then continues to go up from 90C resting to 110-115C under high load. (From 194F to 240F).
 
Originally Posted By: eljefino
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Funny you post this. I have yet to see a decent explanation of this my entire time being here...

You seem knowledgeable with your posts, but this one didn't answer my question at all.
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This is true also! I remember reading from members with separate coolant and oil temp gauges that it takes the oil an extra 10 minutes or so to reach full opp temp after the coolant does
 
CAFE regulations drive U.S. auto suppliers to specify the thinnest (And therefore, most fuel efficient) oil in cars sold here. In Europe, the ME and OZ, there is no incentive for the manufacturer to recommend thin oil, since they do not pay for the fuel.

In my experience, cars seldom die from oil related failures. It is possible to go 300k miles or more on the thin oil specified, with oil never being the issue, as the rest of the car falls to pieces around the engine.

That said......It is your car, so you can use whatever you want. If the manufacturer specs 0W/20, and you want to use 10W/40, there is nothing holding you back except fear and common sense. Oh, and in some engines, the VVT mechanism does not respond well to thick oil.

Personally, since none of my vehicles consume oil, I see no reason to go thicker than the manufacturer's recommendation.
 
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The Higher ACEA A3 HTHS spec lube instead of going up a grade should do it, mate. Shoul;dnt need a 40 in a 30 spec engine unless you are Baja racer or running a lot of heavy throttle opening and load
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Originally Posted By: ARCOgraphite
The Higher ACEA A3 HTHS spec lube instead of going up a grade should do it, mate. Shoul;dnt need a 40 in a 30 spec engine unless you are Baja racer or running a lot of heavy throttle opening and load
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I do sometimes worry that when I show the pedal my shoe, that the 30 weight won't protect the bearings properly. I don't drive hard or like an idiot but I like to kiss the redline every now and then to overtake or have some fun entering the freeway
 
Originally Posted By: 19jacobob93

I do sometimes worry that when I show the pedal my shoe, that the 30 weight won't protect the bearings properly. I don't drive hard or like an idiot but I like to kiss the redline every now and then to overtake or have some fun entering the freeway


Its lugging your engine when hot that causes low oil film thickness, not higher rpm driving. Its the concept of "surfing" the oil film that counts. Stribeck Curve. Lugging is defined as high load at low RPM. When cold, any engine oil has the viscosity to surf, when hot your oil might be too thin.
 
Originally Posted By: dlundblad
I asked this before, but didnt get a straight answer.

Whats the point of running a thicker running weight in extreme heat? We see here that (some) Australians and folks in the Middle East like a 50 or 60 weight oil. Wouldn't the radiator keep oil temperature somewhat in check and prevent any oil related failures? I would also think an oil cooler would be a standard option for vehicles in these regions. We also see engines that spec a much thicker weight in Europe and the other mentioned regions while the identical US version will take a 20 or 30 weight oil. (It has been mentioned here that a European car's severe use yields a thicker oil.. high autobahn speeds for example?)

I don't understand the reason behind any of this. In the US, thin seems to be in while other places are still using a thicker oil.
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I think his question is, since all cars have a cooling system, then other than during warm up, why spec different oils? In effect, a car in Minnesota in winter and a car in Florida in summer, after warm-up should both see the same oil temperature, so why spec a diffent oil.

My answer is, warm-up is a killer of engines. That's when most wear occurs. however, if you are in a warm climate, might as well spec a heavier oil to take advantage of the fact you can.
 
Originally Posted By: philipp10
I think his question is, since all cars have a cooling system, then other than during warm up, why spec different oils? In effect, a car in Minnesota in winter and a car in Florida in summer, after warm-up should both see the same oil temperature, so why spec a diffent oil.

But that is just not the case. Extreme variations in ambient temps do affect oil temperatures, despite your cooling system keeping the coolant temp the same. People often report lower running oil temps during winters up north. And similarly, you might see slightly higher than normal running oil temps during hot southern summers, especially when you're in stop-and-go traffic and not getting much air flow, or if you're just driving in a very spirited manner.
 
Overkill look at the revs, about 6500, its just not the speed he attained but the revs.
Go to the other end of the scale eg a VW Golf 1.6 doing 190 Kmh turning 6500 rpm with no oil cooler will see even hotter oil temps.
 
Originally Posted By: philipp10
Originally Posted By: dlundblad
I asked this before, but didnt get a straight answer.

Whats the point of running a thicker running weight in extreme heat? We see here that (some) Australians and folks in the Middle East like a 50 or 60 weight oil. Wouldn't the radiator keep oil temperature somewhat in check and prevent any oil related failures? I would also think an oil cooler would be a standard option for vehicles in these regions. We also see engines that spec a much thicker weight in Europe and the other mentioned regions while the identical US version will take a 20 or 30 weight oil. (It has been mentioned here that a European car's severe use yields a thicker oil.. high autobahn speeds for example?)

I don't understand the reason behind any of this. In the US, thin seems to be in while other places are still using a thicker oil.
21.gif



I think his question is, since all cars have a cooling system, then other than during warm up, why spec different oils? In effect, a car in Minnesota in winter and a car in Florida in summer, after warm-up should both see the same oil temperature, so why spec a diffent oil.

My answer is, warm-up is a killer of engines. That's when most wear occurs. however, if you are in a warm climate, might as well spec a heavier oil to take advantage of the fact you can.


From my readings you are spot on. The warm up process is what harms the engine more than anything else(lubrication-wise). Starting thinner helps things flow at much cooler temperatures and there are a lot of drivers who only make 10 minute trips meaning things are even up to temp when you're already parking. That is one reason I run a thinner oil than spec. I make a lot of 5 mile and under trips and with a thinner oil it is at least flowing the way my vehicle needs when I shut it down, even if it isn't all the way warmed up yet.
 
So moral of the story, if one sees 115*F+ days on a normal basis, going up a weight or 2 isn't such a bad idea..
 
Originally Posted By: fredfactory
Its lugging your engine when hot that causes low oil film thickness .... Lugging is defined as high load at low RPM. When cold, any engine oil has the viscosity to surf, when hot your oil might be too thin.

And thus I wonder how 0W-20 is a good choice for today's hot running cars with 6-9 speed transmissions programmed to lug for fuel efficiency . Lugging to the point of torque converter shudder which is besides the main point.
I gotta believe that a 0W-30 or 5W-30 is the better option.
 
Originally Posted By: ccap41
Originally Posted By: philipp10
Originally Posted By: dlundblad
I asked this before, but didnt get a straight answer.

Whats the point of running a thicker running weight in extreme heat? We see here that (some) Australians and folks in the Middle East like a 50 or 60 weight oil. Wouldn't the radiator keep oil temperature somewhat in check and prevent any oil related failures? I would also think an oil cooler would be a standard option for vehicles in these regions. We also see engines that spec a much thicker weight in Europe and the other mentioned regions while the identical US version will take a 20 or 30 weight oil. (It has been mentioned here that a European car's severe use yields a thicker oil.. high autobahn speeds for example?)

I don't understand the reason behind any of this. In the US, thin seems to be in while other places are still using a thicker oil.
21.gif



I think his question is, since all cars have a cooling system, then other than during warm up, why spec different oils? In effect, a car in Minnesota in winter and a car in Florida in summer, after warm-up should both see the same oil temperature, so why spec a diffent oil.

My answer is, warm-up is a killer of engines. That's when most wear occurs. however, if you are in a warm climate, might as well spec a heavier oil to take advantage of the fact you can.


From my readings you are spot on. The warm up process is what harms the engine more than anything else(lubrication-wise). Starting thinner helps things flow at much cooler temperatures and there are a lot of drivers who only make 10 minute trips meaning things are even up to temp when you're already parking. That is one reason I run a thinner oil than spec. I make a lot of 5 mile and under trips and with a thinner oil it is at least flowing the way my vehicle needs when I shut it down, even if it isn't all the way warmed up yet.


It isn't the flow of the lubricant that effects wear during warm-up. The oil is pumping and flowing just fine if it is 0w-20 or 5w-50 assuming it isn't -40C out. The issue has several components to it:

- Fit of components when cold is different than when warm. Pistons are looser in their bores. This is one reason some engines have piston slap.
- Fit of rings on cylinder walls is poorer partially due to the first point, which results in blow by gasses going pasting the rings into the crankcase
- Fuel wash on the cylinder walls from the enrichment cycle and cooler cylinder temps. This washes the lubrication from the walls as well.
- Additive heat activation temperature. This is a huge contributor. The additive package in the lubricant, certain components require heat to activate. Member bobbydevro posted on this (as did Shannow) quite recently actually.

This is why we have start-up wear. Once the engine is up to temp; once the additives are activated, parts fit properly, blow-by is reduced, fuel and moisture are flashed off....etc. Then wear becomes as close to zero as it can get.
 
Flat out, do not assume that because the cooling system attains a certain temperature and holds it that your oil temps do the same thing. On a vehcile with guages for coolant temp and oil temp, that is very obvious. I can do so in my vehicles using a scanguage.

On my F150, the coolant temp sits right around 192 under most conditions, with minor up and down fluctuations. Remember that this system is set up with a large radiator and a thermostat to modulate the flow through the system to keep it that way.

The oil temp will settle in from anywhere around 165 in below zero weather to over 200 degrees in 90+ degree weather. There is no oil cooler in my setup. The only way oil can shed heat is through heaat transfer out via the cooling system and by the air moving past the pan.

This is on a setup running 5w20 and a 7 quart pan. You can imagine this may vary dramatically based on use and size of the system.
 
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