Do lower weight oils actually warm faster?

[Ed_Flecko]

Forgive me if this is obvious.

The purpose of lower "weight" (i.e., "grade") oils are to flow better at lower temperatures (and, therefore, hopefully do a better job protecting the motor in said lower temperatures), but do they actually warm up to their normal operating temperatures sooner or do all oils pretty much warm up at the same speed?

I remember seeing a post here recently where someone said that it typically takes about 20 minutes for an oil to reach its normal operating temperature, so I was just wondering if a 5W-30 warms up faster than a 10W-30, and a 0W-30 warms faster than a 5W-30, etc., etc.

Ed

 

[brandini]

Not sure about weight, but I've seen some charts in trade mags showing that synthetics typically have better heat transfer than dino juice, and PAOs better than hydrocracked. Didn't have esters in the chart, sadly.

 

[GenesisGuy70]

My '10 Taurus with 5w20 SEEMS to warm up faster than my '99 Grand Am with 5w30.

 

[Jetronic]

lower weight oils warm up slower, all else being equal. There's less drag inside the bearings, which is one of the thingsthat heat the oil.

 

[nickolas84]

What you are asking is a 2nd degree phenomenon. That means, even if they do take longer to heat up, or have a lower working temperature, that is because they flow better to begin with!

It is like making a car lighter. Traction from the tyres becomes smaller but still the car is more agile.

 

[Lubener]

Technically, they should warm up at the same rate. The end resulting weight would be different. Depends on what you want in the end.

 

[demarpaint]

Originally Posted By: Throt
My '10 Taurus with 5w20 SEEMS to warm up faster than my '99 Grand Am with 5w30.


I think engine design, size, radiator size, thermostat, etc. will have a lot more of an impact. Now if you took the same engine and tested it with a 20 grade vs. a 30 grade under identical temps and conditions your observations would have more validity. You are not comparing apples to apples. Having said that I think a 20 grade oil will heat up and cool off faster, all things being equal.

 

[IndyIan]

I think the higher weight oil actually warms up faster due to its high viscosity. It would take more energy to pump it and also it would cause more drag at a bearing which would heat it further. Shannow did a simple oil temperature test by just running his car at a higher rpm on the road, with the same hp output as he would need for normal driving. The oil temperature was significantly higher due to the frictional losses of just running a bearing faster.
Would thicker oil get to a good operational viscosity faster though? I don't think so.

 

[Rolla07]

In my experience I find in winter it takes my car forever to warm up with 0w20 compared to the dino 5w30 I usually used. I would say 25-30 mins to be back in the middle of the temp range unless I get it on the highway sooner.

 

[HerrStig]

If it takes more power to pump heavy oil, that extra power (pumping loss) is turned into heat in the oil.

 

[Ed_Flecko]

*I* think you're right, bit I also think that's a problem because the oil is still too think to do it's job, i.e., protect the moving parts from wear!

Ed

 

[camrydriver111]

Originally Posted By: HerrStig
If it takes more power to pump heavy oil, that extra power (pumping loss) is turned into heat in the oil.


It would also depend on the overall specific heat capacity of the oil.

If there was no combustion but the engine was still turning over at the same speed. How much heat would be generated? I doubt it would be a lot.

 

[Bgallagher]

Originally Posted By: HerrStig
If it takes more power to pump heavy oil, that extra power (pumping loss) is turned into heat in the oil.


Interesting, never thought of that. Lot of cars were pumping hard this morning in Boston. Brrr!

 

[PandaBear]

Even if it warm up slower, it flows better at lower temperature so you should get the benefit in cold weather.

 

[HerrStig]

Originally Posted By: camrydriver111
Originally Posted By: HerrStig
If it takes more power to pump heavy oil, that extra power (pumping loss) is turned into heat in the oil.


It would also depend on the overall specific heat capacity of the oil.

If there was no combustion but the engine was still turning over at the same speed. How much heat would be generated? I doubt it would be a lot.
Enought to warm the oil itself I suspect, not the block. The thin oil faction tells us that thick oil does run hotter, so I'm just following their lead.

 

[Shannow]

Originally Posted By: HerrStig
Originally Posted By: camrydriver111
Originally Posted By: HerrStig
If it takes more power to pump heavy oil, that extra power (pumping loss) is turned into heat in the oil.


It would also depend on the overall specific heat capacity of the oil.

If there was no combustion but the engine was still turning over at the same speed. How much heat would be generated? I doubt it would be a lot.
Enought to warm the oil itself I suspect, not the block. The thin oil faction tells us that thick oil does run hotter, so I'm just following their lead.


Temperature rise across a bearing from the work that the crank is doing on the oil is around 20F...each bearing consumes a couple hundred watts of power.

So if you think along the lines of a radiant strip heater in the sump, being powered by viscous friction, that's the sort of heating that the drag is doing.

It's lots.

Even in industry, with pumps spinning in plain and michell bearings pumping 50F water we need to install cooling circuits.

 

[brandini]

But it's a flawed question when the goal is to have the proper flow, which would depend on which one is better for that engine.

All back to: As thin as possible and as thick as necessary.

 

[Nickdfresh]

It's not a flawed question. I do use thinner oils (0W-30 M1 AFE) because I'm on the highway in 6 mins or so in some cold temps lately. But I once owned a beater 90' Buick LaSabre that took a very long time to heat up - but ran otherwise very well. I found running a 10W-30 conventional oil made a slight difference for heat in the winter as the engine had nearly 200K on it, though I suspect it might have had a thermostat issue...

 

[brandini]

Originally Posted By: Nickdfresh
It's not a flawed question. I do use thinner oils (0W-30 M1 AFE) because I'm on the highway in 6 mins or so in some cold temps lately. But I once owned a beater 90' Buick LaSabre that took a very long time to heat up - but ran otherwise very well. I found running a 10W-30 conventional oil made a slight difference for heat in the winter as the engine had nearly 200K on it, though I suspect it might have had a thermostat issue...

Great flawed example as well.

It's not the temperature that you want, it's the flow. With the lower viscosity oil, you get to your goal earlier, but the headroom for high temperature could be lowered as well.

 

[Clevy]

I don't think so. However they do get to optimal operating viscosity faster.