Engine Oil degradation study : Tribological Assessment paper

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Dec 13, 2023
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Great paper I recently found that studied degradation of oil and how it affects wear:


TLDR: Change oil by 8k-10k km (5k-6k miles)
They tested a 5W-30 engine oil with all the OE approvals BITOG loves:
• ACEA C3,
• API SN,
• BMW longlife-04,
• MB 229.51, MB 229.52,
• VW 502.00/505.00/505.01 and
• GM dexos2™.

Correlation between increase in wear and decrease in ZDDP.

I guess A3 oils with more ZDDP should have a little longer life
 
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I wonder how much ZDDP is in the NAPA 0W20, I'm gonna use next OCI in the Blue car? I observe the 5k OCI anyway. What do Camrys in EU or AUS spec for oil? :cool:
 
Haven’t gotten the chance to read all citations.

Was this conventional oil? It was tested using turbo charged vehicle. So there’s that, too.
 
So, they ran oil for 20k km and saw 9% increase in friction and 420% increase in wear? No way Sherlock! :ROFLMAO:
That's about 500hrs on oil for an average Joe's driving. There are a couple of big wear increase bumps in graphs that show at about 150hrs and about 250-300hrs for most oils, that we all already know about. That's one of the main reasons I don't take oil over 150hrs and change it usually at about 140hrs based on mileage (4k miles / 6k km); to me it's whichever comes first - either 150hrs or 6k km.
 
Still reading the paper, but I have a VERY hard time believing that a less than .007 increase (~5.2%) in the average COF equates to a 420% wear increase. If that were true and repeatable, it would mean that a 10% change in average COF would result in either 10x longer life (lower COF) or a 1/10 life span (higher COF).

Considering most cars on the road are changed at quickie lubes with the absolute cheapest swill the service provider is willing to put their name on, there would be millions of engines worn out (not necessarily not running) on the road.

Again, haven’t finished the paper, but what was their sample size? And at best, if it was only one engine family, those findings would only apply there, not across all engines. 🤷‍♀️
 
Have you read the paper?
There's a big difference between increased wear rates discerned from oil samples, and actual increased engine functional failures. That's what I was referring to. Big picture data on vehicles tells us at least in the US, vehicles are running longer than ever so the combination of lubes actually being used and product design/manufacturing quality is working well.
 
One thing to keep in mind is that friction and wear are actually not directly related. That explains the 9% increase in friction and 420% increase in wear.
Now show me that wear rate being repeatable, over say 3,000,000 sample engines, and ~75 different engine families. Then I’ll freak out over that, once it’s properly documented, presented, and peer/public reviewed.

Do you sincerely believe that a mere 1% increase in friction brings a 46.7% increase in wear? That means chopping ANY engine’s service life in half, for a 1% increase in friction. That’s what they’re claiming in that paper, and frankly it sounds more ludicrous than any oil marketing I’ve ever heard/seen. Unprecedented, even, and I can’t tell you how much I hate that word!
 
Now show me that wear rate being repeatable, over say 3,000,000 sample engines, and ~75 different engine families. Then I’ll freak out over that, once it’s properly documented, presented, and peer/public reviewed.

Do you sincerely believe that a mere 1% increase in friction brings a 46.7% increase in wear? That means chopping ANY engine’s service life in half, for a 1% increase in friction. That’s what they’re claiming in that paper, and frankly it sounds more ludicrous than any oil marketing I’ve ever heard/seen. Unprecedented, even, and I can’t tell you how much I hate that word!
I don’t really have much of an opinion on their test, but I took it as a relative increase in wear. Not that it would make the engine wear out 4x faster.
 
Still reading the paper, but I have a VERY hard time believing that a less than .007 increase (~5.2%) in the average COF equates to a 420% wear increase. If that were true and repeatable, it would mean that a 10% change in average COF would result in either 10x longer life (lower COF) or a 1/10 life span (higher COF).

Considering most cars on the road are changed at quickie lubes with the absolute cheapest swill the service provider is willing to put their name on, there would be millions of engines worn out (not necessarily not running) on the road.

Again, haven’t finished the paper, but what was their sample size? And at best, if it was only one engine family, those findings would only apply there, not across all engines. 🤷‍♀️
There's a big difference between increased wear rates discerned from oil samples, and actual increased engine functional failures. That's what I was referring to. Big picture data on vehicles tells us at least in the US, vehicles are running longer than ever so the combination of lubes actually being used and product design/manufacturing quality is working well.

In this paper, they took samples of oil from the car as it was running through and tested this sample on both a ball & disc on a tribometer

For sure, the friction coefficient levels can be different than what's in a car and the wear results are indicative.
I remember Lake speed Jr (from Total seal piston rings) saying that wear/friction are separate.

Now show me that wear rate being repeatable, over say 3,000,000 sample engines, and ~75 different engine families. Then I’ll freak out over that, once it’s properly documented, presented, and peer/public reviewed.

Do you sincerely believe that a mere 1% increase in friction brings a 46.7% increase in wear? That means chopping ANY engine’s service life in half, for a 1% increase in friction. That’s what they’re claiming in that paper, and frankly it sounds more ludicrous than any oil marketing I’ve ever heard/seen. Unprecedented, even, and I can’t tell you how much I hate that word!

If you checked the citations, they already did a comprehensive evaluation using regular oil analysis/mass spectrometry methods for multiple gasoline/diesel engines here: https://www.sciencedirect.com/science/article/pii/S0301679X21002279
Some excerpts from this papers:

1713297983574.jpg



1713299185065.jpg

The Iron wear ppm(10-30ppm) is in line with what we see here at BITOG. It doesn't look too terrible but it's there.


It's nice to see that these authors have been working on this topic for a few years now.
All part of AC2T center funded by Austrian university system : https://www.ac2t.at/en/about-us/company/

Here's a 20min article from STLE on AC2T head scientist: https://www.stle.org/files/TLTArchi...bsiteKey=a70334df-8659-42fd-a3bd-be406b5b83e5
 
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