SAE Paper on Engine Wear with 20 wt. oil

Status
Not open for further replies.
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
Way back in early 2000's I had a Ford 4.6l V8 - and they back spec'd from 5w-30 to 5w-20 via a technical service bulleting. That was obviously not due to cafe, so anyone remember why they did so?

There has been all kinds of speculation here over the years I have found in old posts - from Cafe - which can't be true since Cafe has never been back dated - to Ford wants to kill your old car.

People just do not understand physics and MOFT. Yes, under most circumstances a 20-grade oil has sufficient HT/HS to prevent excessive wear. That is why the grade is "back spec'd" to older models. Plus automakers did get retroactive CAFE credits.

However the physics of wear are not some black art that nobody can understand. Even you can. Wear increases with decreasing MOFT, and it is around a typical 20-grade that the curve increases most sharply without design changes to an engine. Since I keep my automobiles for a significant period (and I wish to provide headroom for fuel dilution) there is zero practical downside to an oil with a higher HT/HS. The reverse is true as well, that there are no benefits to an oil with a lower HT/HS besides a marginal fuel economy improvement.
 
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
Our Ford rep told us at the time it was due to camshaft galling in the head. The journals were/are just machined into the aluminum heads without any bearings/bushings. This was in support of our Crown Vic patrol units with the 4.6 V8.
Yes many head designs are like this.
 
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
Better MOFT.

This whole thing about better flow being more beneficial is bunk information. MOFT is how lubrication protects parts. If low viscosity flow is king for protection against wear, then why haven't we been running straight 0 weight oil for the past twenty years? Because we need thicker MOFT than that to prevent contact and wear between moving parts, not just flow.
Yes. The lack of basic physics knowledge coupled with a gross misunderstanding of why lower viscosity oils exist is pretty apparent in this thread.
 
Joined
Dec 6, 2019
Messages
933
Location
South
To the best of my recollection we had only one 4.6 lock up due to cam journal galling. We had such a tight operating budget that we had to use low bid 15W40 (gad & diesel) across all the fleet. Probably not the best but you have to work with what can be afforded.
 
Joined
Jun 3, 2021
Messages
252
There are members here doing exactly that. Towing heavy loads over mountain passes.


A reminder, the W does not stand for weight.
Thank you for enlightening me with this breaking information...

I guess define "heavy" loads then. Find me all these HD trucks pulling 15,000 pound loads up mountains with 20 weight oils. That isn't happening. Gas engines in HD GM trucks for example are still recommending 30 weights, let alone the diesels.
 
Joined
Jun 8, 2022
Messages
1,445
Plus automakers did get retroactive CAFE credits.
Did Ford get retroactive CAFE credits? Only reference to this possibility I can find is HR4011 which was introduced but never passed in 2017, and even had it - that would be 17 years later.
 
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
Did Ford get retroactive CAFE credits? Only reference to this possibility I can find is HR4011 which was introduced but never passed in 2017, and even had it - that would be 17 years later.
No idea about Ford. However, Toyota certainly did, we had a fairly long thread on that a long time ago. The discussion stemmed from their recommendation for 20-grade oils back to vehicles built in the late 90s.
 
Joined
Nov 16, 2002
Messages
35,657
Location
NJ
All engines can run on multiple viscosity grades with HT/HS ranges from 2.3 and > with little issue. It's not an absolute. Never has been. Only a very select few engines need an exact viscosity. But even then, there is also variation within a grade from low to high.
 

Hermann

Site Donor 2023
Joined
Aug 10, 2005
Messages
4,173
Location
Kansas City
The dislike/hate (choose your level) for thinner oils runs deep here. On a new vehicle I will experiment till the engine sounds and feels happy. On my 2008 Tacoma the anemic 4 cyl was so much happier using 5w-20. The engine in my hybrid is liking the Frankenblend. It works out to a 0w-27. Quieter and more refined sounding, is my observation.
 
Last edited:
Joined
Sep 16, 2003
Messages
3,969
Location
Austin, TX MSA
Maybe. This is the chart for my Toyota 2.5 in Australia. Basically you can run anything you like.

Also, in the USA it says you may use 0W-20 if 0W-16 is not available, but you MUST change it back to 0W-16 in 5000 miles - at the next 6 month service interval - rather than the specified 10K interval - or your car will self destruct (well I added the last part, couldn't resist) They give no such warning in Australia.

There are enough thin vs thick arguments on this board that I don't think we need anther, but I think you can infer from this at least that the engine oil viscosity has to do with a lot more than simply lubrication.

I personally don't have an issue running 0w-16 in my engine, but do prefer 0W-20.

View attachment 129488
So 15w40 will work fine for a brand new Toyota hybrid in South Texas for 99.999% of atmospheric conditions.

And if we have an every 30 year cold snap like we did in February 2021 where it got down to 3F a couple of mornings, just leave it in the garage.
 
Joined
Nov 16, 2002
Messages
35,657
Location
NJ
The dislike/hate (choose your level)for thinner oils runs deep here. On a new vehicle I will experiment till the engine sounds and feels happy. On my 2008 Tacoma the anemic 4 cyl was so much happier using 5w-20. The engine in my hybrid is liking the Frankenblend. It works out to a 0w-27. Quieter and more refined sounding, is my observation.
It's not based on science, just gut feelings most of the time. The good news is all engines can run on multiple grades.
 
Joined
Jun 8, 2022
Messages
1,445
Our Ford rep told us at the time it was due to camshaft galling in the head. The journals were/are just machined into the aluminum heads without any bearings/bushings. This was in support of our Crown Vic patrol units with the 4.6 V8.
So the thinner oil provided better flow? Or provided better lubrication as the engine was warming up? Did they provide any explanation. Just curios.

FWIW I had a 4.6. It was find up to 180K when I sold it except for 1 burnt valve at around 80K. Just one - the rest were fine. Had the one valve seat replaced and valves ground ant it was fine the rest of the way.
 
Joined
Jun 8, 2022
Messages
1,445
So 15w40 will work fine for a brand new Toyota hybrid in South Texas for 99.999% of atmospheric conditions.

And if we have an every 30 year cold snap like we did in February 2021 where it got down to 3F a couple of mornings, just leave it in the garage.
Makes you wonder doesn't it.

I run 0W-20. I might go 5W-30 when the warranty is up. I still wonder about how all this plays with the variable volume oil pump. Toyota doesn't care beyond 100K.
 
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
So the thinner oil provided better flow? Or provided better lubrication as the engine was warming up? Did they provide any explanation. Just curios.
Flow isn’t important. It’s the film thickness that prevents wear and protects the engine. This is what gives better lubrication as the engine is warming up and at all other times.
 
Joined
Dec 26, 2005
Messages
23,729
Location
Upper Midwest
I run 0W-20. I might go 5W-30 when the warranty is up. I still wonder about how all this plays with the variable volume oil pump. Toyota doesn't care beyond 100K.
It doesn’t except for what that gets you in terms of reduced engine load.

Again it helps when you understand that there are no benefits to thinner oils except fuel economy. If that is your sole objective then go for it.
 
Joined
Jun 8, 2022
Messages
1,445
It doesn’t except for what that gets you in terms of reduced engine load.
I find that exceptionally hard to believe. If that were the case why not simply run lower volume all the time. Instead they have a complex ECU controlled algorithm based on calculated engine load and rpm.
 
Status
Not open for further replies.
Top