Engine teardown with weight comparison?

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Hi. I think this may be the best sub to ask in.

I know it's probably unlikely, but has anyone ever done comparisons of engines that have similar miles that have run different weight oils? For example 3 taxies that went into service in the similar time that ran with 5w-20, 5w-30 and 5w-40 oil in them for their lifetime and compared later to see the wear differences?
 
I remember one poster here saying that he worked at a Ford shop (or was he doing training?), and they tore down engines that were running 5w30, and also the newer ones with 5w20. He said that they looked the same, but that the 5w20 ones were cleaner around the pistons.

I'll try to find that thread. Wish me luck.
smile.gif
 
The sample size isn't large enough or controlled enough, usually; you need fleet data.

Best source of readily (web) available data would be public utilities like maybe a State School Bus or Police fleet or (if you can find it) military sources. They do these kinds of things from time to time, and they will have cost-benefit data to go with it, which is what you really want.

There are almost certainly other sources, but the problem is getting the data from private sources, whom might see it as competitive-restricted or proprietary information.
 
I'm sure this will matter to some people, but my main thought is on the long term protection. I don't mind paying a bit more for fuel if it means a little more peace of mind, even if it is only a small amount of peace.
 
I'm disappointed with the amount of data out there. Surely there must be police garages, or taxi garages that have tried long term tests using different oils. Also, you would think there would be more info from our Universities and colleges. Just downright disappointing.
 
For what its worth, in the mid 90s, Toyota did some testing with oils that had an HTHS equal to 20 and 30 weight, and found that the 20 weight oils recorded fairly equal engine wear (this was oils with an HTHS of 2.6 and 3.1). They even threw in an oil with 2.4 HTHS and found that in most of their tests, even that oil did well. Unfortunately the text was in Japanese, but the charts showed the results.

Try this link: https://www.beamium.com/v/ZVYVMTDM

The site takes a while to upload the next page when you click on the right arrow, but it does go from one page to the next.
 
Last edited:
BullittGT: Deposit on a Bullit I see. Awesome. Best looking machine.

It does depend on the engine model. Recommended weight in the Owner's Manual is what the engineers know will pass their durability testing, and thats plenty.
The more surface area and the less loading on bearings governs how viscous the oil has to be to provide a non-zero thick oil film. So its engine design as much as anything that governs the question.

5w20 (or 0w20) is all a lot of engines need. I would go up to a 5w30 on an xw20-spec engine if towing or racing in hot weather just to be sure it doesn't thin too much.
Push the video slider to the 1:44 point to see how a 5w20 does very well in a Ford 4.6L engine:
 
Originally Posted By: oil_film_movies
BullittGT: Deposit on a Bullit I see. Awesome. Best looking machine.

It does depend on the engine model. Recommended weight in the Owner's Manual is what the engineers know will pass their durability testing, and thats plenty.
The more surface area and the less loading on bearings governs how viscous the oil has to be to provide a non-zero thick oil film. So its engine design as much as anything that governs the question.

5w20 (or 0w20) is all a lot of engines need. I would go up to a 5w30 on an xw20-spec engine if towing or racing in hot weather just to be sure it doesn't thin too much.
Push the video slider to the 1:44 point to see how a 5w20 does very well in a Ford 4.6L engine:


I don't know that I can agree on the part part of your post bolded in italics above; I recall reading on here somewhere that the oil recommendation in the owner's manual is required to be the oil used for CAFE figures, and ONLY the oil grade used for those figures. Seems to me if that's what the government is requiring, then the engineers no longer write the manual in that respect.


edit: there's also a video of the Schaeffer Oil 1,000,000 mile van engine teardown:

https://www.youtube.com/watch?v=hDF1zcaxrNU

That engine was super clean and showed no measurable wear either.

I emailed the company (Schaeffer) awhile back, they said that they had used 15w40 diesel oil in the Ford 5.4L gas V8.
 
Originally Posted By: paulri
He said that they looked the same, but that the 5w20 ones were cleaner around the pistons.

Is he suggesting that the straighter oil resulted in cleaner rings? I'm shocked.
 
Originally Posted By: JLTD
I don't know that I can agree on the part part of your post bolded in italics above; I recall reading on here somewhere that the oil recommendation in the owner's manual is required to be the oil used for CAFE figures, and ONLY the oil grade used for those figures. Seems to me if that's what the government is requiring, then the engineers no longer write the manual in that respect.

The EPA (CAFE people) have never required the use of xw20 oils.
The automakers have turned to xw20 oils to get about 1% better fuel economy compared to using xw30 oils, and that does count on the EPA FTP MPG CAFE.
Note its the automakers choice to use xw20 to get 1% better CAFE. They didn't have to do it. Never forced to.

That said, the engineers have been designing engines to keep the Stribeck Curve in the same or similar position by making the bearing surfaces larger to accomodate xw20 oils. Durability remains the same or similar.
It is true engines spec'ed to xw20 will run just fine on xw30 oil, with a small MPG penalty. Automakers do perform durability testing to be confident xw20 oils aren't too thin to sacrifice durability.
 
Originally Posted By: BullittGT
I'm sure this will matter to some people, but my main thought is on the long term protection.
All else being equal, operating viscosity matters for components protection. It's physics.

Originally Posted By: paulri
Try this link: https://www.beamium.com/v/ZVYVMTDM

Quote:
Abstract of Toyota research says:
Lowering the viscosity of engine oil is effectice in reducing the fluid friction.
However, it decreases the oil film thickness, and causes the increase in the wear of the engine parts.


But does it matter to others, that's a different issue altogether.
 
The sentence you quoted is followed by another, that summarizes the findings:

Through the engine wear tests using an [sic] radioisotope tracer technique, it was clarified that an HTHS viscosity of 2.6 mPa-s was the lower limit to prevent the increasing wear.


Originally Posted By: zeng
Originally Posted By: BullittGT
I'm sure this will matter to some people, but my main thought is on the long term protection.
All else being equal, operating viscosity matters for components protection. It's physics.

Originally Posted By: paulri
Try this link: https://www.beamium.com/v/ZVYVMTDM

Quote:
Abstract of Toyota research says:
Lowering the viscosity of engine oil is effectice in reducing the fluid friction.
However, it decreases the oil film thickness, and causes the increase in the wear of the engine parts.


But does it matter to others, that's a different issue altogether.
 
http://pdf.blucher.com.br.s3-sa-east-1.amazonaws.com/engineeringproceedings/simea2016/PAP20.pdf

Low viscosity oils impact on Heavy Duty Diesel engine components

Edney Deschauer Rejowski, Dr. Eduardo Tomanik, Juliano Pallaoro Souza
MAHLE Metal Leve SA (Downloadable)

Compares "a SAE15W-40 (HTHS 3.7cP) currently used in Brazil and a 10W-30 (HTHS 2.9cP) candidate for the European next generation engine" but looks at some 0W/x oils as well. Lots of graphs and photos showing greater wear on the lower viscosity oil, though the thicker oil showed more blowby, which I wouldn't have expected (see table 2)
 
I liked the Kendal video and they deserve credit for making the effort to figure what it was that was wearing on the engine.
However, the Kendal was synthetic oil and the other oil was conventional so pretty useless as an oil to oil comparison.

I noticed there seems to be some accusations that the use of 20 weight oil is only a a gas mileage thing and there are folks suggesting that the engineers do not agree with it. I don’t buy into that assessment. The film strengths on these synthetics are so good they can now take advantage of the lower friction of the lower viscosity. Looks to me the lack of wear and tear on that engine helps to support that.

By the way, Exxon does not own a taxi fleet. Geesh.
 
Originally Posted By: paulri
For what its worth, in the mid 90s, Toyota did some testing with oils that had an HTHS equal to 20 and 30 weight, and found that the 20 weight oils recorded fairly equal engine wear (this was oils with an HTHS of 2.6 and 3.1). They even threw in an oil with 2.4 HTHS and found that in most of their tests, even that oil did well. Unfortunately the text was in Japanese, but the charts showed the results.

Try this link: https://www.beamium.com/v/ZVYVMTDM

The site takes a while to upload the next page when you click on the right arrow, but it does go from one page to the next.


Thanks! I'll give it a read once I get a moment. I've barely even had time to respond to this thread. HA!


Originally Posted By: oil_film_movies
BullittGT: Deposit on a Bullit I see. Awesome. Best looking machine.

It does depend on the engine model. Recommended weight in the Owner's Manual is what the engineers know will pass their durability testing, and thats plenty.
The more surface area and the less loading on bearings governs how viscous the oil has to be to provide a non-zero thick oil film. So its engine design as much as anything that governs the question.

5w20 (or 0w20) is all a lot of engines need. I would go up to a 5w30 on an xw20-spec engine if towing or racing in hot weather just to be sure it doesn't thin too much.
Push the video slider to the 1:44 point to see how a 5w20 does very well in a Ford 4.6L engine:


Thanks, I had a deposit on a Performance Level 2 GT that a dealer is holding to apply to the BULLITT once the orders open. As soon as I heard that Dark Highland Green was returning I was sold.
 
Originally Posted By: oil_film_movies
Originally Posted By: JLTD
I don't know that I can agree on the part part of your post bolded in italics above; I recall reading on here somewhere that the oil recommendation in the owner's manual is required to be the oil used for CAFE figures, and ONLY the oil grade used for those figures. Seems to me if that's what the government is requiring, then the engineers no longer write the manual in that respect.

The EPA (CAFE people) have never required the use of xw20 oils.
The automakers have turned to xw20 oils to get about 1% better fuel economy compared to using xw30 oils, and that does count on the EPA FTP MPG CAFE.
Note its the automakers choice to use xw20 to get 1% better CAFE. They didn't have to do it. Never forced to.

That said, the engineers have been designing engines to keep the Stribeck Curve in the same or similar position by making the bearing surfaces larger to accomodate xw20 oils. Durability remains the same or similar.
It is true engines spec'ed to xw20 will run just fine on xw30 oil, with a small MPG penalty. Automakers do perform durability testing to be confident xw20 oils aren't too thin to sacrifice durability.


Perhaps I should clarify my position. I don't believe I said that CAFE requires 0w20; I said that CAFE requires manufacturers to specify only the oil used to get the CAFE number.... a finer point but one nonetheless. We're on the same page there.
 
There is data; plenty of it.
Most of you just ignore it.

https://bobistheoilguy.com/used-oil-analysis-how-to-decide-what-is-normal/

Over 12,000 UOAs in the data base.

Brand and grade do NOT matter in normal applications. Period. The typical variation of everyday equipment use (car, trucks, vans, tractors, generators, diesel, gasoline, NG, LPG, etc) is far greater than what you'll be able to show that vis has any effect.
 
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