Wear vs Viscosity

[ZeeOSix]

An oil is not going to get to operating temp when it's -50 ambient. Considering the KV of a 50wt is close to 20 at 100c, what is it going to be when the oil is only sitting at 75c?

What temperature the oil gets to at operating temperature depends a lot on the engine. Obviously in your extreme -50/-60C degree use example the oil won't get as hot unless measures were used to allow it to. But you're cherry picking some extreme example that wouldn't happen in real life unless someone is totally uneducated on what oil viscosity (mainly the W rating for the cold start) to run based on the ambient use conditions of the vehicle.

And besides, even if the operating temperature of the 15W-50 grade oil was at 75C, it's not going to "blow-up" the engine up. What's going to blow it up in your 15W-50 at super cold start-up example is the cold start-up because the oil won't pump at -50C and the oiling system won't get any oil.

 

[ZeeOSix]

Well viscosity is the most important part I would think. But oils are blended with many components, so the end product matters most. The stress levels used for the HTHS test are indicative of those in the bearings of engines. Stresses seen in the ring, bore or lifter are said to be higher.

Everyone should know the distinct difference between film thickness and film strength. The film thickness due to viscosity is the primary protection to keep rubbing parts separated and from rubbing/wearing, and the film strength is the AF/AW additives that provides the tribofilm on parts that takes over wear mitigation when the film thickness goes to zero due to lack of viscosity. The AW/AF add pack is definitely important for parts in mixed and boundary lubrication, as is the parts material make-up - ie, cam lobes in boundry lubrication need to be of the correct material make-up to survive in that lubricatiion realm.

The Importance of Lubricant Film Strength

Discover why film strength is one of the most critical lubricant properties for protecting a machine’s internal components.

www.machinerylubrication.com

 

[TurboZedd-R]

What temperature the oil gets to at operating temperature depends a lot on the engine. Obviously in your extreme -50/-60C degree use example the oil won't get as hot unless measures were used to allow it to. But you're cherry picking some extreme example that wouldn't happen in real life unless someone is totally uneducated on what oil viscosity (mainly the W rating for the cold start) to run based on the ambient use conditions of the vehicle.

And besides, even if the operating temperature of the 15W-50 grade oil was at 75C, it's not going to "blow-up" the engine up. What's going to blow it up in your 15W-50 at super cold start-up example is the cold start-up because the oil won't pump at -50C and the oiling system won't get any oil.

I was just answering a question on when thicker oil doesnt protect better. More of a snarky ridiculous example for a typical snarky comment. But still valid.

 

[ZeeOSix]

I was just answering a question on when thicker oil creates more wear. Regardless if it is extreme, it is a valid example.

A 50 grade at an operating temperature of 75C isn't going to cause more wear. Can you reference any SAE studies or similar that shows when a too thick of oil starts causing more wear after the engine temperature has stabilized? Every time you cold start your engine (even in the summer time) and drive until it's warmed up the the oil goes through a range of thickness much more than that on the way to the end operating temperature. If engines were damaged from running with thicker oil, they'd all be worn out after all their cold start-ups and running on oil viscosity anywhere between 1000s of cSt on the way to full operating viscosity of 8-18 cSt depending on the KV100 grade and operating oil temperature.

You ever been to the drag races? Guys sit in the staging lane for an hour on a chilly night and the oil is cooled way down. They push the cars and never start them until they are ready to run the 1/4 mile. They fire up the engine and do a big burn-out, then hammer it all the way down the 1/4 mile at WOT and redline. The oil is never at full operating temperature, and many may be running a xW-40 or xW-50 motor oil. They do this every weekend, yet they aren't blowing up their engines. It's certainly pretty hard on them, but anytime you hammer an engine at WOT to redline for any extended time the loads are maximized and that alone will cause more wear, especially if the viscosity it not adequate.

 

[kschachn]

I was just answering a question on when thicker oil doesnt protect better. More of a snarky ridiculous example for a typical snarky comment. But still valid.

Answer being when it is too thick to be pumped because of an inappropriate winter rating.

 

[paulri]

Buster, what is the source for that graph? I looked in the link you provided and didn't see it there.

Well viscosity is the most important part I would think. But oils are blended with many components, so the end product matters most. The stress levels used for the HTHS test are indicative of those in the bearings of engines. Stresses seen in the ring, bore or lifter are said to be higher.

View attachment 245276

Thread 'VII (VM), shear, base-oil viscosity, HTHSV, friction, and wear: State of the art'

Jun 5, 2019

I will discuss a recent paper on the subject in this thread.

• Gokhan
• Replies: 17
• Forum: White Papers and Technical Discussions

 

[gfh77665]

I drive my Civic very gently, as MPG is my concern there so I’m completely comfortable with an oil that is around 8cst at 100c. I really don’t believe that I would benefit going thicker in the Civic because of my driving style. I rarely go above 50% throttle in this car and the engine spends 99% of its time at 1700 rpm or less. It simply doesn’t need that extra viscosity at all. On the other hand, I drive the Corvette differently and I like to go full throttle when I have a clear stretch of road so that is why I want an oil that is closer to 12 cst. I believe those choices are perfect for my driving style and will result in long engine life out of both cars.

Thats a perfect example of someone thinking.

Likewise I don't hate thin oils at all. In Northern tier of USA and all of Canada, I am using 0- or 5-20. Mid America, 5w-30 is great. Sunbelt, 10w-30 is optimal in most cases. I disregard one-size-fits-all-CAFE.

 

[buster]

Buster, what is the source for that graph? I looked in the link you provided and didn't see it there.

Sorry I don't remember LOL. I have it saved on my pc. Let me see if I can track down where I pulled it from.

 

[TurboZedd-R]

Answer being when it is too thick to be pumped because of an inappropriate winter rating.

Hence 15w50 in Yukon Canada

 

[jetman]

 

[cryptolyme]

When doesn’t it?

when it doesn't flow fast enough

 

[ZeeOSix]

when it doesn't flow fast enough

Refer back to using the correct W rating. The W rating was invented for a reason, so people don't use oil that's too thick for cold starting conditions. All oil grades are going to flow more than adequate when at operating temperature. A PD oil pump is used in engines to ensure adequate flow to critical parts.

 

[thetricky]

An oil is not going to get to operating temp when it's -50 ambient. Considering the KV of a 50wt is close to 20 at 100c, what is it going to be when the oil is only sitting at 75c?

Here is where our thermostatically controlled cooling systems come into play.

 

[kschachn]

when it doesn't flow fast enough

If the pump can pump the oil then it will flow fast enough. The problem is when it cannot be pumped, and that is illustrated by the winter rating.

As is nearly always the case it isn't about flow. The only flow that matters is near the pump pickup tube.

 

[BigCahuna]

I own 2 GM vehicles that were made to run 5w30 wt oils. One eats that wt oil to the tune of 1 qt,every 750 miles. The other doesn't consume any oil between changes. The differences between them is, one is a 4 cyl and holds 5 qts of oil, and the other is a 6 cyl, and holds 6 qts of oil. One thing I did to help the oil drinker, was to change it to 10w40 wt oil. It has under 100k miles on it and doesn't leak or smoke. There are no cel's on, so I can't say where the oil goes. I stopped using oil with GM's Dexos approval ,as I found it doesn't do or mean anything,as far as engine operation goes. The big engine runs fine on 5w30,and doesn't use any oil between changes. Also it has less 50 k miles on it. After 50 years of owning various brands and models of cars and trucks, I've found that as long as you keep some brand or type of oil in your vehicle, the engine will always outlast the rest of the vehicle. Getting nit picky over brand or specs of your oil,mean nothing in the long run.,,

 

[kschachn]

I own 2 GM vehicles that were made to run 5w30 wt oils. One eats that wt oil to the tune of 1 qt,every 750 miles. The other doesn't consume any oil between changes. The differences between them is, one is a 4 cyl and holds 5 qts of oil, and the other is a 6 cyl, and holds 6 qts of oil. One thing I did to help the oil drinker, was to change it to 10w40 wt oil. It has under 100k miles on it and doesn't leak or smoke. There are no cel's on, so I can't say where the oil goes. I stopped using oil with GM's Dexos approval ,as I found it doesn't do or mean anything,as far as engine operation goes. The big engine runs fine on 5w30,and doesn't use any oil between changes. Also it has less 50 k miles on it. After 50 years of owning various brands and models of cars and trucks, I've found that as long as you keep some brand or type of oil in your vehicle, the engine will always outlast the rest of the vehicle. Getting nit picky over brand or specs of your oil,mean nothing in the long run.,,

Good to know, perhaps I should just use any 30-grade in my Tiguan rather than the $27 ESP I currently use.

 

[BigCahuna]

Good to know, perhaps I should just use any 30-grade in my Tiguan rather than the $27 ESP I currently use.

Got any personal, long term real world proof your $27 esp, makes anything work better ?.,,

 

[Patman]

Got any personal, long term real world proof your $27 esp, makes anything work better ?.,,

The real world proof is looking at all of the approvals that ESP has in comparison to other 0w30 and 5w30 oils. Getting many of those approvals is not an easy task, that’s why you don’t see every other Xw30 oil carrying them. That’s more than enough proof for me to have chosen 5w30 ESP to run in my Corvette.

 

[wpod]

When doesn’t it?

When it doesn't.

 

[kschachn]

The real world proof is looking at all of the approvals that ESP has in comparison to other 0w30 and 5w30 oils. Getting many of those approvals is not an easy task, that’s why you don’t see every other Xw30 oil carrying them. That’s more than enough proof for me to have chosen 5w30 ESP to run in my Corvette.

Yes that is the real-world proof.