Oil Temp Rise and Viscosity

[SR5]

I was reading the Diesel Truck area and DustyRoads, made the following interesting post. I didn't want to hijack the thread, so I'll ask my question here.

What is the relationship between viscosity, rate of temperature rise and final operational temperature?

It seems a 40 weight synthetic runs cooler and heats up slower than a 40 weight mineral. They may have the same Viscosity at 100 C, but the mineral should have a higher viscosity at lower temps and maybe this heats the oil faster.

Originally Posted By: dustyroads

Most of my trucks from a '97 Detroit to a '12 Volvo had the oil temps regulated at 210 and going into the 230's and 240's pulling the mountains out west. I recently traded in a '13 Volvo that allowed the oil to run up to 246-247 before cooling it. It was free to run anything up that point.

Running 15W40 for three oci's, it would run up there near the cutoff most of the time, constantly hitting the limit then cooling, and then shooting right back up. This was without climbing mountains, just cruising at near 80k lbs.

When I switched to 10W30, it took much longer to hit the 247f limit. It would get there but it took 3-4 times the miles after the cooling cycle compared to the heavier oil.

I then tried Rotella T6 (5W40) for one oci and the oil temps seemed to run even cooler. When pushing it hard in high winds and/or climbing long hills it would eventually get up to 247f to get the oil cooler to kick in but it was the slowest to climb up to that point. Mostly, oil temps remained in the mid to upper 230's using T6.


Obviously for racing and heavy duty you want to run cool. But should maybe short trippers run a slightly thicker (or lower VI) oil to heat things up faster. Given reasonable winter start ratings of course.

 

[Shannow]

SR5,
a 15W40 WILL warm up faster than a 5W40, as there's more viscous drag in bearing surfaces (bearings, piston skirts etc).

The 15W40 will likely have an HTHS in the low to mid 4s, while the 5W40 will more likely be around 3.8. The 15W40 will generate more heat when running than the 5W40, so that observation stands true.

the 10W30 is presumably an HDMO, and will have an HTHS in the 3.6 ish range, so on the road there will be far less difference between the 10W30 and the 5W40 than either of them and the 15W40.

The quoted differences in miles between heat cycles seem a little extreme IMO.

Here's a little experiment that I did with my mower, 5W20 and 20W60...

Originally Posted By: Shannow
I decided to test that this morning, on my Briggs Quantum mower.

Have been using 5W20 synthetic through winter (grass hasn't died off at all this year it's been so mild).

Mowed this morning, then left it sitting at the Governor for 10 mins or so. Temperature of the oil (thermocouple down dipstick hole) was 87C.

Changed oil to 20W60...97C.

For explanation, that's the new equilibrium temperature that the oil has to sit at to dissipate the extra work the engine is doing against it.

 

[Shannow]

And here's a pic from a paper on accelerating engine warmup, which mentions.

Pic shows the internal heating that's generated within the oil in the warm-up phase, and includes comparison to heat conduction into the oil through piston crowns et al.

It's only a little 1.7L donk, but there's 4KW of oil heating taking place early in the warmup...this heat also goes into heating the coolant and the metal surfaces, by passage through the main bearings and bulkheads...but that 4KW is just over 5hp worth of fuel burned at that point.

A higher VI oil will result in less heating there, and a slower warmup, as per the quote you used...will also use less power.

The Japanese, in papers, state that's the primary driver for the ultra high viscosity index oils, to reduce fuel consumed in the warmup periods, particularly in hybrid situations that don't establish full oil temperature in many cases.

 

[SR5]

Thanks Shannow, what you say makes sense to me.

In my car on 10W-40 semi-syn, there was a bit of engine ticking on start-up but it quickly went away, and stayed away for the rest of the day.

Now I'm using 5W-40 full synthetic, no ticking on immediate start-up, but the ticking comes in a few minutes as the car slowly warms, and stays for a very long time. Every time you stop the car (shops, school) it has a massive ticking fit on start-up and again stays for a long time.

It spends most of it's day ticking and tapping, making me feel like I'm driving around in Woody Woodpecker's car. When it finally warms up, it's beautiful and smooth and just purrs along. It reaches this nice stage most often as I'm coming home for the night.

I've been thinking about it a lot, and I just think my oil is taking too long to heat up for my driving style. It would be fine if I drove a few hundred km at a time, but I'm not covering enough distance.

I think I need a lower VI oil that warms up quicker.

 

[Shannow]

SR5,
remember VI is just a dimensionless number comparing the viscosity at 40C and 100C versus what was the best of the mineral sources 100 and something years ago.

The KV (and more importantly the High shear) viscosity at the point in the range is the variable, the VI just describes it.

Look at these two...

Delo 15W30

Castrol EDGE 5W40

From an Australian perspective where even the 15W won't be taxed, and operating between freezing and highway, I would expect the two oils to be indistinguishable (from a viscosity perspective)

 

[yvon_la]

His truck has issue. Oil temp and water temp are regulared by thermostat . If i recall 2 for oil and 2 for water. often water thermo has only one checked. Oil thermostat ?they Re never checked. i wont go into detail because it isnt directy relevent but 18wheeler vehicule have bad preventive maintenance. You go to a scale truck is fine. But if the scale guy coud speak to the mechanic that fix the truck.the scale person woud likely tell them to start doing preventive maintenance

 

[Shannow]

SR5,
can't believe that you weren't part of this thread

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3881570

 

[SR5]

Thanks, I'll check out that thread.

Yes, I know VI is not an absolute quantity, more relative change in viscosity.

I was more referring to the 40 weights I have been using, but I'm also thinking of stepping down my oil to a 30 weight.

 

[dustyroads]

Hey SR5, I can add a couple specifics.

The 15W40 was Kendall Super D-xa with a listed HTHS of 4.4 but I can't find anything for the other oils. The 10W30 was Delvac Elite and as mentioned I also used T6.

Also, the 15W40 took about 1.1 - 1.3 miles to go from 239F up to the cutoff of 246-247F (238-239 was the temp after a very brief cooling cycle.

The 10W30 would bump the upper limit within 3-4 miles and then cooled again. The T6 was going about 5 miles between the cooled temp up to the 247f cutoff but only when working fairly hard. It ran cooler than the 10W30 when not using a lot of boost.

This was all while chugging along between 1,000rpm and 1,150 rpm. The truck was setup for super low rpm cruising using high torque.

No there weren't any problems with the truck. My previous ('12) Volvo was also programmed to run those same high temps. However, the first time I went into a dealer for warranty work they reprogrammed the ECM to cool the oil sooner. They set it to regulate the oil at 210 just like every other truck I had owned. Volvo was finding problems that they thought were maybe related to the higher oil temps but my 2013 Volvo was never reprogrammed .

I'm only passing along what I saw while running the truck, nothing more. I'm happy running 15W40 and 10W30.

Edit- the T6 seemed to cool quicker when stopping the truck and idling at 600 rpm. That's not something I timed with a watch but it seemed clear to me that it was cooling from near 240 down to 210 much quicker than the others.

 

[yvon_la]

As for your oil question? There is an article about it not in forum but on bobistheoilguy.com that dude speak about his ferari or was it corvette and his experience with oil. He answer all your question.i dont follow his teaching for warranty reason.

 

[SR5]

Originally Posted By: dustyroads
Hey SR5, I can add a couple specifics.

The 15W40 was Kendall Super D-xa with a listed HTHS of 4.4 but I can't find anything for the other oils. The 10W30 was Delvac Elite and as mentioned I also used T6.

Also, the 15W40 took about 1.1 - 1.3 miles to go from 239F up to the cutoff of 246-247F (238-239 was the temp after a very brief cooling cycle.

The 10W30 would bump the upper limit within 3-4 miles and then cooled again. The T6 was going about 5 miles between the cooled temp up to the 247f cutoff but only when working fairly hard. It ran cooler than the 10W30 when not using a lot of boost.

This was all while chugging along between 1,000rpm and 1,150 rpm. The truck was setup for super low rpm cruising using high torque.

No there weren't any problems with the truck. My previous ('12) Volvo was also programmed to run those same high temps. However, the first time I went into a dealer for warranty work they reprogrammed the ECM to cool the oil sooner. They set it to regulate the oil at 210 just like every other truck I had owned. Volvo was finding problems that they thought were maybe related to the higher oil temps but my 2013 Volvo was never reprogrammed .

I'm only passing along what I saw while running the truck, nothing more. I'm happy running 15W40 and 10W30.

Edit- the T6 seemed to cool quicker when stopping the truck and idling at 600 rpm. That's not something I timed with a watch but it seemed clear to me that it was cooling from near 240 down to 210 much quicker than the others.


Hi DustyRoads,
Thanks very much for that. Very interesting observations.

Interesting how the T6 5W-40 synthetic seemed to cool quicker. I feel my Shell Helix Ultra 5W-40 synthetic is doing the same, but I can't prove anything.

 

[SR5]

Originally Posted By: Shannow
SR5,
can't believe that you weren't part of this thread

https://bobistheoilguy.com/forums/ubbthreads.php/topics/3881570


That's a great thread, yes I can't believe it slipped past me the first time. Very Interesting and lots of useful advice.

I'll start by putting my auto car in "D2" for a few km, to get the revs up a bit. I have been using "D3" instead of "D4" because that's closer to the revs I would be using in a manual gear box.

 

[SR5]

Exactly 5 months ago I changed the oil on my family 4-cylinder car. It's an GM/OPEL/Holden Astra that requires an A3/B3 or A3/B4 oil in 30 or 40 grade, according to the OM.

I used Shell Helix Ultra 5W-40, a GTL full synthetic that's SN, A3/B4, MB 229.5, BMW LL-01, etc. Plus I used a new Repco Z154 oil filter. Straight away it developed a loud (lifter?) tick when cold. On starting it was fine for the first 3 KM, then a loud tick could be clearly heard, that didn't go away until the car was fully warm at 20KM. When warm it was smooth and quiet, but stop the car for a few minutes and straight away you would have the tick again. People would stare at me as I drove past in the car park after shopping. (average temp ~ 33 C).

Did about 3500KM on the oil, no improvement, so I added about 150ml of LiquiMoly MoS2. This reduced the sounds level a little, but no real improvement.

After 3 months and 4000KM, I dumped the oil (SHU 5W-40) and tried a full mineral oil. As per DustyRoads above, to try and get the car to warm up quicker. I used Castrol GTX 15w40 (SN, A3/B3), but I kept the exact same filter on. Changing only one variable at a time. The nose was slightly quieter, but the pattern on cold start was much the same. Silent for the first 3 KM, then lifter tick until 20KM. From 15KM to 20KM it was quiet under load / high RPM, but ticked at idle and low RPM. All up no big improvement. (Average temp ~ 20 C).

Another 1500KM, and I kept the oil in this time (GTX 15w40), but I changed out the oil filter. I removed the Repco and replaced it with a WesFil - Cooper WZ154. Filter only change. This made a noticeable improvement. From cold start, all silent, a bit of a soft ticking phase from 6KM to 12 KM, and pretty much all over by 15KM. People no longer stare at me in the shopping centre car park. Much Better. (Average temp ~15 C).

Due to school and work duties, I drive the same roads everyday at the same time. The traffic is pretty constant, but it's been cooling down over the months.

So I believe my lifter tick was due to a restrictive oil filter. The Cooper is much better than the Repco (Z154) filter.

Next on the list is to try a 30 grade oil and maybe one of those low restriction Ryco SynTec oil filters.

 

[Silk]

I don't like the Repco filters, you don't know where they are made, I usually try to get a Ryco 99% of the time. The Z154 is an odd looking filter and doesn't seem to have a ADBV, but has been on the 3.8 forever.

 

[SR5]

Hey Silk,

Yeah I'm off Repco filters now. Do you want to buy some ? I have two left.

The Z154 does have an ADBV, and the do work, I tested it when I removed the old filter.

Have you tried the Cooper filters before ? I've heard (mostly) good things about them. Australian company, but the filter is made in China "to Wesfil Australia specifications", for whatever that is worth.

 

[zeng]

Originally Posted By: SR5
I was reading the Diesel Truck area and DustyRoads, made the following interesting post. I didn't want to hijack the thread, so I'll ask my question here.

What is the relationship between viscosity, rate of temperature rise and final operational temperature?

It seems a 40 weight synthetic runs cooler and heats up slower than a 40 weight mineral. They may have the same Viscosity at 100 C, but the mineral should have a higher viscosity at lower temps and maybe this heats the oil faster.

Originally Posted By: dustyroads

Most of my trucks from a '97 Detroit to a '12 Volvo had the oil temps regulated at 210 and going into the 230's and 240's pulling the mountains out west. I recently traded in a '13 Volvo that allowed the oil to run up to 246-247 before cooling it. It was free to run anything up that point.

Running 15W40 for three oci's, it would run up there near the cutoff most of the time, constantly hitting the limit then cooling, and then shooting right back up. This was without climbing mountains, just cruising at near 80k lbs.

When I switched to 10W30, it took much longer to hit the 247f limit. It would get there but it took 3-4 times the miles after the cooling cycle compared to the heavier oil.

I then tried Rotella T6 (5W40) for one oci and the oil temps seemed to run even cooler. When pushing it hard in high winds and/or climbing long hills it would eventually get up to 247f to get the oil cooler to kick in but it was the slowest to climb up to that point. Mostly, oil temps remained in the mid to upper 230's using T6.


Obviously for racing and heavy duty you want to run cool. But should maybe short trippers run a slightly thicker (or lower VI) oil to heat things up faster. Given reasonable winter start ratings of course.


Could it be Moly and Boron from T6 5w40 has skewed Dustyroad's observations vis-a-vis 15W40 and 10W30 ?

 

[SR5]

Not sure what 30 grade oil to try next. Probably not a synthetic, as I'm experimenting a little and changing early.

Thinking either
Caltex / Chevron Delo Silver SAE 30 (API CF/SJ) monograde mineral
KV 40 = 90 cSt, KV100 = 11.5 cSt,

Or
Castrol Magnatec 10w30 (API SN, ACEA A3/B4) semi-synthetic
KV 40 = 84 cSt, KV100 = 12.4 cSt

Both should have a HTHS of around 3.5 to 3.6 cP (I assume).
The Magnatec is the sensible option, but I'm itching to try a HDEO mono-grade if it's not too silly an idea.

Right now I'm running
Castrol GTX 15w40, (API AN, ACEA A3/B3) mineral
KV 40 = 113 cSt, KV100 = 14.5 cSt, HTHS = 3.95 cP

What do you think, a multigrade 10w30 or a mono-grade SAE 30 ??

 

[ChrisGuerrero]

Shell Rotella T6 15w40 provides extra protection against breakdown by heat and offers up to 70% better oxidation resistance and provides excellent low-temperature flow, even at -30ºF.

 

[Jetronic]

Originally Posted By: Shannow
And here's a pic from a paper on accelerating engine warmup, which mentions.

Pic shows the internal heating that's generated within the oil in the warm-up phase, and includes comparison to heat conduction into the oil through piston crowns et al.

It's only a little 1.7L donk, but there's 4KW of oil heating taking place early in the warmup...this heat also goes into heating the coolant and the metal surfaces, by passage through the main bearings and bulkheads...but that 4KW is just over 5hp worth of fuel burned at that point.

A higher VI oil will result in less heating there, and a slower warmup, as per the quote you used...will also use less power.

The Japanese, in papers, state that's the primary driver for the ultra high viscosity index oils, to reduce fuel consumed in the warmup periods, particularly in hybrid situations that don't establish full oil temperature in many cases.


at 33% efficiency, wouldn't that be 15 hp worth of fuel? and 5 hp less power?

 

[SR5]

A few recent posts on Castrol Magnatec and Wesfil Cooper filters reminds me that I should finish up this thread.

So, I still have the nice Wesfil Cooper filter in the car. See this nice cut and post from Chrismo
Cooper Filter C&P

Then I changed the oil to semi-synthetic Castrol Magnatec 10W30 (SN, A3/B4), and it is the smoothest oil I have ever used in this car.

Not perfect, as there is still a bit of warm up noise under light throttle for a small time and in much the same pattern as before, but better than anything else I have used. No noise at idle and no noise under heavy throttle. When there is a tapping noise at light throttle, it's much softer than before, and goes away fairly quickly.

I have mentioned this before, but for the first two weeks, I was so surprised by the smoothness of Magnatec 10w30 at idle, that I often found myself looking at my instrument cluster while stopped red traffic lights to ensure my car was still running. It was so smooth, I thought the engine had stopped, but it was always running fine. I don't look down anymore when stopped as I'm more accustomed to it.

So Magnatec 10W30 and a Cooper filter is a good, affordable and easy to find combination that is working for me. A sensible guy would just stick to these two and get on with more important jobs.