Going by HTHS

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Originally Posted by userfriendly


Why do chipped and deleted diesels often drop their cranks on the pavement?

Maybe it's because 3.8-4.3 HTHS is no longer sufficient to float the loaded rod bearing with the added torque.


Excellent thought....a pumped up diesel putting out 1,200 ft-lbs (1626 Nm) on a system manufactured for 1/2 that is bound to need a little help with boundary layer film strength.
 
Originally Posted by StevieC
I think I'm going to go back to 5w20 when my 0w30 OCI is done. I have enough miles in a short amount of time it will be a perfect test case to prove there is nothing wrong with 20wt and lower HTHS that is still within the limits of the OE specification.

Heck I'll even do UOA's along the way with the Wix $10 kits for trending.


I don't understand why this is even a thing.

2015_PSD and I both ran "severe service" conditions using 20 weight oil in our Ford trucks.

I went quite a few steps over the deep end by using Mobil's 5000 mile conventional oil for more than 9000 miles, on the second OCI of a previously installed filter. During the OCI, whenever my truck was not towing 2 tons over it's tow rating, it was being driven very hard by me.

2015 towed 8000 lbs routinely. We both subjected our trucks to this in summer heat. Both of our trucks well beyond 100k miles.

We both produced UOA results beating that of many Ford 5.4s driven under much better conditions, doing half the miles over an OCI.

20 weight oil rarely gets such a torture test.

It's not a debate. 20 weight oil can be simultaneously subjected to a long and horrible life in a heavy vehicle towing even heavier vehicles and overachieve anyway.

The only thing that is possibly a debate at this point is if OEMs are recommending 20 weight oils for engines that really aren't engineered for a 20 weight oil. There's no argument otherwise.
 
Originally Posted by userfriendly
My go-to summer oil for my LML Duramax is 50/50 Duron SAE30 & SAE 40.

40C 110
100C 12.7
150C 3.8


Back in the day, Duramax listed SAE 30 and 10W30 as optional grades. Then the horsepower and torque was increased and the 30 grades were dropped.

The 2017-2019 L5P has redesigned rod bearings, but again the torque and horsepower is higher. (T910, HP 445). The two grades listed in the owner's manual are 5W40 and 15W40 depending on ambient.

Typically the HTHS on those two grades are between 3.8 and 4.3

My mono-grade blend has the lowest KV100C that yields the minimum 3.8 HTHS required.

Why do chipped and deleted diesels often drop their cranks on the pavement?

Maybe it's because 3.8-4.3 HTHS is no longer sufficient to float the loaded rod bearing with the added torque.


To be fair, the Duramax crankshaft issues are hardly an oil issue. If we are to believe many Duramax gurus, it's a firing order issue.
 
Originally Posted by StevieC
Originally Posted by caprice_2nv
Originally Posted by StevieC
I intend to drive the van until the wheels come off which should be far past what a normal person will keep their vehicle for which will make the "worry" about using 0w40 in 5w20 application irrelevant.


It's pretty clear that no amount of facts or test results that don't agree with your opinion will change your mind on the subject.

Btw, the highway driving you do that racks up the miles that fast creates much less wear than doing 300-400k miles over 35-40 years (for example my daily driver and what I hope to get out of it). So making a choice based on real test results (instead of Stevie's opinion from the UOAs he's seen here) would likely make more of a difference in my case. I also have the unknown wear already put on by the first few owners over 27 years of probably the cheapest conventional oil to worry about.

And the vehicles over the past decade filled at Jiffy Boob with 5w20? Guess the OE's should shorten warranties on the 0w16 Camry and the vehicles in the future coming with 0w8.
smirk2.gif



Warranty is short enough. I didn't see anyone saying that using a 20 weight isn't good enough to go the warranty period or even a short life of 200k or 300k. You're still not commenting on what I said at all.
 
Btw my mom has gone 220k miles on her Taurus 3.5 with 5w20. Of course it's been highway driving and 3k mile intervals (I didn't tell them they had to change that frequently - so no need to comment on that). "Easy on oil" engines like this or your Pentastar aren't convincing anyone of anything.

This subject has been brought up mostly because of direct injection and or turbo engines. Not old Ford's that lasted forever on 5w20.

Let everyone discuss what is "best" for the engine and not just what is "good enough". Once you're at 400k miles and a bearing spins it's not like you can rewind time and switch weights or OCI or whatever. If you know you'll be happy to buy something new and scrap the old one at that time then it doesn't matter at all. But for some people it might.
 
Originally Posted by JLTD
Originally Posted by userfriendly


Why do chipped and deleted diesels often drop their cranks on the pavement?

Maybe it's because 3.8-4.3 HTHS is no longer sufficient to float the loaded rod bearing with the added torque.


Excellent thought....a pumped up diesel putting out 1,200 ft-lbs (1626 Nm) on a system manufactured for 1/2 that is bound to need a little help with boundary layer film strength.

And how does unnecessarily high hths equate to boundary layer film strength?
 
Originally Posted by madeej11
Originally Posted by JLTD
Originally Posted by userfriendly


Why do chipped and deleted diesels often drop their cranks on the pavement?

Maybe it's because 3.8-4.3 HTHS is no longer sufficient to float the loaded rod bearing with the added torque.


Excellent thought....a pumped up diesel putting out 1,200 ft-lbs (1626 Nm) on a system manufactured for 1/2 that is bound to need a little help with boundary layer film strength.

And how does unnecessarily high hths equate to boundary layer film strength?


Maybe go back through and read the entire thread; Shannow and oil_film_movies put out some really good information that will answer your question.

"Unnecessarily high hths...." is simply inflammatory....as one member states in his signature: as thin as possible, as thick as necessary.

I'm not saying that anyone should go for maximum HTHS.
 
Originally Posted by madeej11
Originally Posted by JLTD
Originally Posted by userfriendly

Why do chipped and deleted diesels often drop their cranks on the pavement?

Maybe it's because 3.8-4.3 HTHS is no longer sufficient to float the loaded rod bearing with the added torque.

Excellent thought....a pumped up diesel putting out 1,200 ft-lbs (1626 Nm) on a system manufactured for 1/2 that is bound to need a little help with boundary layer film strength.

And how does unnecessarily high hths equate to boundary layer film strength?


You want both film thickness and film strength.

Film thickness is what keeps moving parts from contacting each other. HTHS is related to how much film thickness you'll get from the base oil/viscosity under extreme temperature and shearing conditions.

Film strength can be described as the lubricant's ability to lessen the effects of friction and control wear by means other than the film thickness. The film strength is dependent on the wear and friction-​control additives in the base oil.

https://www.machinerylubrication.com/Read/30835/lubricant-film-strength
 
If we were to take a 50s or 60s designed V8, triple the power output from its original design, maybe add NOS which if brought in at low RPM drastically increases torque, would an engine oil with a higher HTHS than originally specified be necessary to keep the bearings and journals separated?

Could the oil pressure be increased instead of running a thicker oil?

Could the bulk oil (sump) temperatures be lowered instead of using a thicker oil?

Granted, thicker engine oils produce more heat from fluid friction, so an oil cooler would not be a bad idea if and when running thicker oils.
 
Originally Posted by userfriendly
If we were to take a 50s or 60s designed V8, triple the power output from its original design, maybe add NOS which if brought in at low RPM drastically increases torque, would an engine oil with a higher HTHS than originally specified be necessary to keep the bearings and journals separated?
Yes. Temperature in the rings & the gudgeon pin went up, needing more HTHS to maintain lubrication.

Originally Posted by userfriendly
Could the oil pressure be increased instead of running a thicker oil?
With a huge power increase, yes more oil pressure, maybe 20% more with triple the power to help cool the parts. Still need a thicker oil though.

Originally Posted by userfriendly
Could the bulk oil (sump) temperatures be lowered instead of using a thicker oil?
Yes, cooler oil is thicker, and even when hitting the hot pistons, its useful to start out cooler.
 
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