Confessions of a Recovering Thickie

[ZeeOSix]

Yes. So stay within the range.

There's also the disclaimer.

"GM dexos R engine oils meet or exceed the performance of GM dexos 2 and GM dexos 1 Gen 2 and Gen 3 oils and are backward compatible, therefore vehicles equipped with gasoline engines that used GM dexos 2, or GM dexos 1 Gen 2 or Gen 3 may use a GM dexos R licensed engine oil of the appropriate viscosity grade at their next oil change.
https://www.gmdexos.com/brands/dexosr/index.html

If I want to run a 0W-40 or a 5W-50 for instance on the track, then it is the right viscosity for me. Even if I wanted to run a dexos R 5W-50 in a Coyote, just like Ford does on say the Boss 302 or Track Pack Coyote, then it's the right viscosity for me.

 

[siriusc1024]

AKA euro oil. Right back where we started.

Ugh lol.

 

[siriusc1024]

If I want to run a 0W-40 or a 5W-50 for instance on the track, then it is the right viscosity for me. Even if I wanted to run a dexos R 5W-50 in a Coyote, just like Ford does on say the Boss 302, then it's the right viscosity for me.

If I want to run 0w-20 in a Nissan Rogue on public roads that's the right viscosity for me.

The LS gets 5w-30.

 

[ZeeOSix]

If I want to run 0w-20 in a Nissan Rogue on public roads that's the right viscosity for me.

The LS gets 5w-30.

I'd go "rogue" and run a xW-30 ... no matter what engine specifies a xW-20. What's wrong with more engine protection? It's not like sun on a vampire ... but seems that way to some, lol.

 

[ltslimjim]

I'd go "rough" and run a xW-30 ... no matter what engine specifies a xW-20. What's wrong with more engine protection? It's not like sun on a vampire ... but seems that way to some, lol.

Seems pretty simple to me. Reasonable. Might not matter, but could help over the lifespan of ownership of the engine and in some use cases. Certainly doesn’t hurt, as long as you have the appropriate winter rating. So, what am I missing?

 

[Overfill]

It can also fail to ingress in sufficient quantity to non-pressurized locations.

?

 

[Glenda W.]

If I want to run 0w-20 in a Nissan Rogue on public roads that's the right viscosity for me.

The LS gets 5w-30.

Honestly I’d step up to the ESP 0w30 in both, not only for simplicity but also to keep those engines and pistons clean. Dexos has a hard time in that department. I’m dealing with a clean up test as we speak from QS 0w20 synthetic on 5k oci’s.

 

[hemioiler]

Why would you present your argument that way? No need to distort the data. In terms of percent, friction is reduced 8%-25%. Just because it's a decimal number doesn't mean tiny.

I have a 0.00005% chance of stepping out my door at 4PM and getting hit by a bus. At 5PM, my chances go up by 50 percent to 0.000075%.

By percent increase, that looks absolutely terrible (50% increase). By actual decimal numbers, it's absolutely nothing.

Should I care at what time I step out into traffic?

 

[ZeeOSix]

There are tradeoffs and various considerations from an engineering standpoint as well. Too high viscosity makes bearings run hotter. It can also fail to ingress in sufficient quantity to non-pressurized locations. Don't neglect the importance of oil volume and cooling.

The bearing temp increases is hair splitting - doesn't matter as long as the MOFT is more than adequate. If people run too low of a viscosity in track use for instance, the oil still gets way hotter than normal, and then the MOFT goes to zero and the bearings get worn or damaged. Based on your logic, all engines running thicker than a xW-16 would be damaged from the oil causing the bearing temperature to rise. They aren't. Again, why do you think high performance engines run thicker oil - maybe they should run some 0W-16 at the track and keep those bearing "cool" until they start glowing orange from no MOFT and blow through the side of the block, lol.

"It fails to ingress in sufficient quantity to non-pressurized locations" - only if the wrong "W" rating is used for the start-up conditions. Even a 0W is pretty thick when really cold.

 

[Synth vibes]

I have been poring over the UOA section looking at every UOA I can find. It sure seems to me that if you plotted wear metal rate per 1000 miles against viscosity grade, you'd have incredibly weak correlation. The R-square has to be under 10%. There are some outlier datapoints, but within the realm of modern fuel-injected gasoline cars with more than ~40k miles on them, you will see about 1ppm/1k miles of iron, which is the primary wear metal.

You run supertech or Kirkland? You'll see about 1ppm/1k miles.
HPL or Ravenol? You'll see about 1ppm/1k miles.

If you are a fan of thin oils and run 0w20, you'll see about 1ppm/1k miles of iron.
If you are a fan of thick oils and run 5w40, you'll see about 1ppm/1k miles of iron.


If you have over 2ppm/1k miles of iron, you are a BITOG outlier.

I'm forced to confess the reality that while I prefer heavier oils with low to no VII content (SAE 40, yeah baby!), there's no evidence in our UOAs that says you are significantly extending engine life vs some thinner oil that is also sufficiently protective.

Sufficient is sufficient. Being more sufficiently thick doesn't change anything but burn more fuel. Think of it this way: what can you do with a net worth of $100 billion that you cannot do with a net worth of $20 billion? Nothing, really. In both cases you are crazy rich. The fact that one is 5x the other amounts to nothing, really.

I think that's what's sort of at work here. I can, under duress of data, confess that my preference for thicker oil is emotional, not intellectual.

I thoroughly appreciate you not only making a decision based on logic and data, but sharing it with us. I have been here on another profile, or lurking since when pennzoil platinum first took over (2009-2010ish). A lot of people have made claims based really only on their opinion that thin oils are bad. Or CAFE is a psyop/flat earth vibes. Glad to see this kind of mindset trickling down here too. I know people mean well, and really we all are here because we want to make good decisions when it comes to caring for our vehicles. But in reality it is good to make those decisions based off data, logic or both, and not what your uncle said 50 years ago. Now I just cant wait for the every 3k miles that converted to every 5k people to give that up too. really 7k + on the oils and filters people run here would most likely be fine. Probably could find data to back that up as you have.

 

[ZeeOSix]

Here's the bearing temperature rise between 0W-20 and 0W-30. A whole whopping 1.5 deg C (2.7 deg F) at 4000 RPM.

 

[ZeeOSix]

The red line at around the 10-20 degrees crank angle (the power stroke where MOFT gets very small) is why you might want some MOFT headroom from thicker oil. This is also why rod bearings show wear on the top half. 300 MPa is 43,511 PSI. The more power the engine can put out, the higher the rod loads.

 

[kschachn]

I thoroughly appreciate you not only making a decision based on logic and data, but sharing it with us. I have been here on another profile, or lurking since when pennzoil platinum first took over (2009-2010ish). A lot of people have made claims based really only on their opinion that thin oils are bad. Or CAFE is a psyop/flat earth vibes. Glad to see this kind of mindset trickling down here too. I know people mean well, and really we all are here because we want to make good decisions when it comes to caring for our vehicles. But in reality it is good to make those decisions based off data, logic or both, and not what your uncle said 50 years ago. Now I just cant wait for the every 3k miles that converted to every 5k people to give that up too. really 7k + on the oils and filters people run here would most likely be fine. Probably could find data to back that up as you have.

So you’re basing all of this on UOA too?

 

[kschachn]

Here's the bearing temperature rise between 0W-20 and 0W-30. A whole whopping 1.5 deg C (2.7 deg F) at 4000 RPM.

View attachment 280649

Yes the whole “bearings run hotter” is a bit of a joke.

 

[kschachn]

?

Translated: the passages are too small.

Before the drive gear is sheared off the electric oil pump, but before it can get through the tolerances that are too small.

 

[ZeeOSix]

They also tend to run the tightest practical clearances to reduce the leakage rate with thinner oils. The tighter clearance thing is generally good, because tighter clearances increase the load capacity of a journal bearing.

The bearing load capability is basically a function of the bearing surface width and surface area. If the bearing surface area is too small and there isn't enough MOFT (due to inadequate viscosity) to withstand the force on the bearing, the MOFT is going to zero (see graph in post 272). This is why engines designed for low viscosity 0W-8 and 0W-16 have larger/wider journal bearings.

Also, a thinner oil results in a more nonuniform pressure distribution inside the bearing. The higher the Pmax/Pav ratio, the more nonuniform the pressure distribution. When all aspects of the effects of oil viscosity on journal bearings is looked at, there are way more negatives than positives when the viscosity is lower.

 

[siriusc1024]

Translated: the passages are too small.

Before the drive gear is sheared off the electric oil pump, but before it can get through the tolerances that are too small.

I specifically mentioned parts that don't have a pressurized oil supply. That's many. I know you might not be familiar with engines, but that doesn't excuse the profoundly terrible reading comprehension.

 

[Hohn]

The bearing load capability is basically a function of the bearing surface width and surface area. If the bearing surface area is too small and there isn't enough MOFT (due to inadequate viscosity) to withstand the force on the bearing, the MOFT is going to zero (see graph in post 272). This is why engines designed for low viscosity 0W-8 and 0W-16 have larger/wider journal bearings.

Also, a thicker oil results in a more nonuniform pressure distribution inside the bearing. The higher the Pmax/Pav ratio, the more nonuniform the pressure distribution. When all aspects of the effects of oil viscosity on journal bearings is looked at, there are way more negatives than positives.

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Good post, but I have no idea how it related to my point on *clearances* being minimized.

 

[siriusc1024]

Honestly I’d step up to the ESP 0w30 in both, not only for simplicity but also to keep those engines and pistons clean. Dexos has a hard time in that department. I’m dealing with a clean up test as we speak from QS 0w20 synthetic on 5k oci’s.

If you think the ESP will provide better protection and oil pressure than Mobil 1 0w-40 FS then I might be willing to try it. I already commented on my experience with FS in a previous post. I honestly think M1 oils start out great but wear down quickly. I think the base stock sucks and they compensate with additives. That's just my opinion.

Right now I use QS Synthetic 5w-30 in the LS, QS Synthetic 0w-20 in the Rogue. 5k OCI on both. M1 filters.

As far as cleanliness with Dex lemme show ya. I just walked out and snapped this for you. This is my head bolt. I put a dash on the head bolts with permanent marker for degree torque. Rocker on the left (hint of bronze if you look closely by the snap ring). Bright aluminum casting in the head. I did the head swap 80k ago.

With the Rogue I'll confess that I have put 5w-30 in it once. Only once. Idea was to get better protection. See, I've already had this thick vs thin discussion with myself. The reasoning is that Nissan not only recommends but requires 0w-20 in that engine. I've already expressed how important it is to make consideration for the engine architecture when deviating from spec. I can't find enough information to make a good informed decision. Especially, now that I know about the existence of piston ring coatings commonly found in mpg-focused engines, I'm leery of going thicker. I'll stick to the spec.

 

[siriusc1024]

The bearing load capability is basically a function of the bearing surface width and surface area. If the bearing surface area is too small and there isn't enough MOFT (due to inadequate viscosity) to withstand the force on the bearing, the MOFT is going to zero (see graph in post 272). This is why engines designed for low viscosity 0W-8 and 0W-16 have larger/wider journal bearings.

Also, a thicker oil results in a more nonuniform pressure distribution inside the bearing. The higher the Pmax/Pav ratio, the more nonuniform the pressure distribution. When all aspects of the effects of oil viscosity on journal bearings is looked at, there are way more negatives than positives.

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I just want to point out what you said in bold. See, I mentioned that before. This was the response:

Engines aren’t designed “for” a grade. Any grade that isn’t too low of an HT/HS can be used.

Plus your use of winter ratings in the examples show you don’t really understand this.

I respect that you are capable of making a sensible argument, even if we're on the opposite side sometimes. Some people are more concerned about being right than what's right. It's unfortunate.

Very good info on pressure distribution and relationship to viscosity. Hadn't considered that, but I'll keep it in mind from now on.

Notice also they mention decrease clearance to compensate for thinner oils. Another design feature with viscosity in mind. Do you think there are any risks of inadequate lubrication for thicker oils in bearings clearanced with thinner oils in mind?