Random Oil Question

[mbacfp]

Hello all,

Is there a negative on oil breakdown the number of times an oil goes from cold to hot. I know short tripping a car hurts oil by not getting moisture burn off, etc. Does cold to hot, hot to cold have any negatives to an oil or its additives? Hope everyone is well.

 

[NVRENUFF]

The heat cycles have no ill affects on oil breakdown as long as the heat is within normal range. The accelerated wear on vehicles that are driven short trips is wear from so many cold starts. People still debate the amount, but it's pretty well agreed that 65-80% of an engines wear comes from cold starts. IMO a vehicle driven around town short trips would benefit from a sticky additive like Lucas or shell X100. It helps oil stick to the bearing surfaces to reduce cold start wear.

So many people claim to be experts and say it's bad to idle a vehicle for extended periods. I work in the oil industry and my service vehicles run and idle from 12-18hrs a day, 7 days a week. My though was to reduce the cold start wear since that's at least 65% of an engines wear. My duramaxes have had 400,000 miles and 22,000 engine hours and still ran like new. No blowby, stock injectors, stock turbos, stock everything. I have 2500 Chevy express vans with 4.8L gas motor and they have upward of 16,000hrs on the motors. All stock and still running strong.

 

[69GTX]

Every cycle from cold to hot has to transition through the range where the oil additive package is not fully functional. That results in some wear/corrosion/etc. to engine parts. The oil as a minimum loses some TBN as the additives get used. In a nut shell, the cold to heat cycle definitely abuses the oil. The acids that are formed during a cold startup and heat up will get neutralized by the add pack once at temperature. If you want the maximum life on your oil and/or vehicle, don't ever let the oil get cold...or as few times as possible. Most of the engine wear (90%) occurs from the cold to hot transition, not the first couple seconds....but the first 10-20 minutes. during those first few seconds as oil pressure/flow build up to normal, your engine parts are fairly well protected by the oil's cold viscosity and film boundary layer protection....not to mention whatever protective chemical layer is still intact on your moving parts.

 

[mbacfp]

Thanks for the great info. Appreciate your time.

 

[dnewton3]

Originally Posted By: NVRENUFF
.... People still debate the amount, but it's pretty well agreed that 65-80% of an engines wear comes from cold starts.



I would actually disagree.

For your claim to be true, we would see a large disparity in UOA data analysis. For it to be true, cars that do short trips and many frequent starts would show wear data trends that would be 60-80% greater. After all, if the precept is that most wear comes at cold starts, then that metal from the wear would have to reside in the lube, and therefore would show up in a UOA. You cannot have "wear" and not get the resulting "wear metals"; they cannot just vanish. So if that claim is to be true, we'd see macro data average nearly twice for some vehicles. But we don't. I've got about 15k UOAs in my database now, and I'm confident that just isn't true at all.

Further; this:
http://papers.sae.org/2007-01-4133/

The TCB (tribochemical barrier) develops in the first few thousand miles. As it matures, wear rates actually drop on a magnitude of about 10x, despite any/all manner of use. Short trips, long idles, steady state; it does not matter.

I think that concept you refer to is old-skool thinking and it is deeply rooted. But real data and facts say otherwise.

 

[mbacfp]

Thanks Dnewton. What do you make of Castrol's claim with Magnatec. I see your logic with the UOAs, but I am assuming Castrol did some UOAs as well plus engine tear downs, etc. I've seen this debate on here before...just curious what your thoughts are on Magnetic. Thanks.

 

[dnewton3]

I generally don't pay any attention to marketing claims, so I cannot comment as I've not researched their specific issue.

I will way this, though ...
Let's presume I'm wrong; let's say (despite all my data and the SAE study), that 60-80% of all wear does occur on cold starts. So what? What perspective are we using here?

We see lot's of vehicles that actually do this type of "severe" service here on BITOG. We see the UOAs from these types of vehicles. And yet, they still motor on happily, and turn in great UOAs. So even if 60-80% of all wear comes from these colds starts, it's still completely "normal", and the overall effect of wear spread over the OCIs is moot.

Think of it in terms of some theoretical limits; we'll just make up some arbitrary numbers for the sake of the example:
Car "X" is subjected to a slew of cold starts daily, and it sheds 70% of it's metals during the first few moments of running. It's showing 2ppm Fe / 1k miles.
Car "Y" is run at near steady-state on the highway, and while it accumulates the same miles, it has 60% fewer cold starts. It shows 1.2 ppm Fe / 1k miles.
While it is true in this mythical example that "X" has "70% more wear" at cold start, it's meaningless because BOTH cars have excellent wear rates.
This is the concept of "just how good does something have to be, to be considered "great" versus "good"?. How much of a good thing pushes one into "greatness"?
Conceptually, this is like two drunkards debating who's raising the level of the ocean more by urinating into the stream behind their house. One may contribute 60% more volume than the other, but it pales in contrast to the overall effect of the liquid volume.

What we see in UOA macro data is that everyday normal variation from lube to lube, car to car, environment to environment, etc to etc, makes for "normal" wear trends. What this "cold start wear" concept introduces is a niche within a niche. It's so silly-small that, while it may exist in a true sense, that sense is just about imperceptible in everyday use.

And, I refuse to ignore the data from SAE 2007-01-4166 that shows wear rates will drop to "near zero" as the OCI matures. Those cars in that study were run nearly non-stop operation; had very few cold starts. So that is a baseline for what a warm engine will produce. And yet when I compare data from other similar vehicles with many multiple cold starts, I see the exact same phenomenon; that of wear rates dropping as the OCI matures, to super low levels.

Do cold starts contribute to more wear? Macro data does not show that to be of any consequence, regardless if it's true or not.

Therefore, I don't really care what lab experiment some marketing team is relying on to sell their premium lube.

 

[Shannow]

Originally Posted By: dnewton3

Further; this:
http://papers.sae.org/2007-01-4133/

The TCB (tribochemical barrier) develops in the first few thousand miles. As it matures, wear rates actually drop on a magnitude of about 10x, despite any/all manner of use. Short trips, long idles, steady state; it does not matter.


That paper specifically took a bunch of oils, some of which were completely totalled as in having thickened well out of grade and TBN, and measured the development of a tribofilm under test conditions of metal on metal with new and used oil.

The study, as we have been over, and over, and over, and over...does not in any shape or form demonstrate that which you keep attributing to it.

 

[69GTX]

So do wear rates drop substantially from the first 3K miles of an OCI to the next 3K miles? If so, it would be strong evidence to avoid any oil change under approx 3K miles for infrequently driven vehicles. At the same time it would violate mfg guidance of not exceeding 1-2 yrs between oil changes, regardless of miles.

 

[dnewton3]

Originally Posted By: Shannow
Originally Posted By: dnewton3

Further; this:
http://papers.sae.org/2007-01-4133/

The TCB (tribochemical barrier) develops in the first few thousand miles. As it matures, wear rates actually drop on a magnitude of about 10x, despite any/all manner of use. Short trips, long idles, steady state; it does not matter.


That paper specifically took a bunch of oils, some of which were completely totalled as in having thickened well out of grade and TBN, and measured the development of a tribofilm under test conditions of metal on metal with new and used oil.

The study, as we have been over, and over, and over, and over...does not in any shape or form demonstrate that which you keep attributing to it.



Did the three lubes thicken? Yes.
Did TAN cross over TBN? Yes.

So what? Other than stating the obvious, what effect was there? You're bringing up points that essentially have no merit other than as a diversion tactic.

The point I make is salient and it exactly what they make of it too; wear rates drop as the oil matures because of the TCB. Once the TCB is established, the wear goes down. The TCB is established generally in the first few thousand miles, and the wear rates drop after that is formed. But the acid cross over, and oil vis increase, do not correlate to any of the wear trend data. Once again, your constant objections to the usefulness of the study are moot and based on a false sense of purpose.

Allow me to quote from the study:
"It is interesting to note the viscosity of the 7500 mile drain oil is about 20% higher (at 100c) than that of the 3000 mile drain oil and therefore, might be expected to show a lower wear rate because of increased oil film and the resulting reduction in asperity contact. But both oils showed similar wear rates indicating that the wear rate is controlled more by the chemistry of the surface film at the contact than asperity contacts."

IOW, for those of you whom don't understand what you read ... the wear rates were unaffected by the viscosity change. Because there is no correlation, there can be no causation.

The lube thickened and the acid flipped, and it made absolutely no difference in wear rates. I am at a loss to understand why you bring those two topics in from the periphery, as if they matter. Sir - they don't matter and that very point is directly addressed in the study.

What did change that precipitated the wear reduction? The development (thickness) of the tribochemical barrier.
Their conclusion (and mine) is valid; the TCB is the majority controller of wear rate reductions.


And this phenomenon is echoed in my UOA data research and analysis. There are lubes that will thicken from oxidation, but not all will. Specifically, PAOs don't thicken much; that's part of their benefit. And yet the wear rates will change in the PAO OCI duration, just as with other lubes that do thicken. It's not just these three lubes in the SAE study. No - it's generally ALL lubes in ALL engines that show this affect. There are tons of UOAs that show no thickening whatsoever and the wear rates drop with the OCI. There are other UOAs that show a significant shift in vis, and yet the wear rates do the very same thing. This is a phenomenon that is NOT, none whatsoever, explained by vis and crossover.

Why you cannot understand this, when they point it out directly, is beyond me.