What if "low tension ring" theory is all wrong?

[SubieRubyRoo]

It's unfortunate that we guinea pig consumers are the ones who pay for these questionable improvements. Engineering isn't cheap.

One wonders if the end user recoups sufficient individual fuel savings to compensate - including ongoing maintenance and repair costs.

I doubt the end user ever sees an actual measurable benefit, especially with the myriad ways A/S/S is defeated. About the only place it would ever realize full benefit is city driving only, where neither AC or heat was ever used; i.e. windows-down territory all-year round.

As far as I know, a place like that does not exist in the US, as even Key West, the only US city to have never recorded freezing temps, has gotten down into temps too cold for all but the heartiest to risk those chills.

But I’m fairly sure we’ve seen downsides to the stop/start. Not in every case, but higher than the rate at which an engine familiy’s non-stop/start brethren experience, and potentially statistically higher. But nobody that I know of has a database with that level of macro data in it in a single place.

 

[burbguy82]

the oil is not up to the task of the design and requirements

 

[oil pan 4]

It's been a whirlwind 24 hours. I'm coming up for air now.

This is a summation of Dr Rudnick's work in Lubricants and Lubrication (2nd ed) and also Lubricant Addtives: chemistry and applications. I was able to then ask a bunch of questions and dang if it wasn't mind-blowing in several ways. Because the conversation included so many references to specific chapters and pages of these works, I feel like a got a pretty good Cliff's Notes of these enormous volumes. I suppose perhaps the AI was gaslighting me the entire time, and I am just that gullible. But it all made sense to me as explained.


What I found most mind-blowing of all, however, was the suggestion that the modern epidemic of sticking rings might have more to do with oil oxidation and little to nothing to do with "low tension rings." After all, here on BITOG it's mostly accepted as gospel that modern engines all have "low tension rings" and these rings all suck and that's why all new engines are junk and turn into oil burners.

But what is the *mechanism* by which being lower tension would cause the rings to develop deposits? Lower tension also means narrower in thickness. The result is that the rings have lower tension because they don't need as much tension to generate the same outward sealing pressure values. "Low tension" as a standalone explanation for piston ring groove deposits and resulting oil consumption is just wholly unsatisfactory as an explanation.

So what is actually contributing to the epidemic of stuck rings?


[edit by moderator - AI image removed]



The analysis continues as follows:




So what does this suggest to me?

It suggest to me that the modern problems with ring sticking have perhaps nothing to do with "low tension" rings. But, like low tension rings, it is in fact a product of the government mandated push for CAFE and enhanced fuel economy, but ring sticking is a phenomenon of oil oxidation in the ring pack, and low HTHS oils are much worse for ring pack oxidation. If the oils below 3.5 HTHS are 25-40% worse in ring pack deposit simulations than oils that are >4.0 HTHS, then how much worse are these oils that are 2.7-2.8 HTHS in ring pack oxidation?

In other words, we seem to be mistaking correlation for causation-- that because "low tension rings" coexist with low viscosity oils and sticking rings, that the the ring sticking is *caused* by the lower tension. However, the low tension may just be coexisting with the lighter oils, which may be the real contributor to stuck rings. Especially so in dilution-prone GDI or TGDI engines where the ring pack films are even more heavily compromised by dilution that can be double what the sump dilution is.


I never considered viscosity and cleanliness to be related in this way. But I'm seeing in the "Rudnick commentaries" many smaller ways in which thicker oils lead to cleaner, happier engines-- less tendency to generate crankcase aerosols (huge for GDI), thicker films which are actually very useful at light loads, etc.

This is just one of the many aspect of this deep dive with "Dr Rudnick" that sort of blew my mind, but it was by far the most consequential, in my opinion. If anyone wants me to share other insights from this deep dive with "Dr Rudnick", just say the word and I'll put those in another thread.

View attachment 305152

Been running ultra low tension oil rings since 2009. Rings go no sticky yet.
But I also change my oil at about half of what oems are saying to change the oil in current vehicles.
Only time I've seen stuck rings was on engines that had gone way over recommended oci, had a Kubota with stuck rings with 3,400hrs on the OCI, had a slight oil leak and needed top off oil, that's probably the only thing that saved it.

 

[SubieRubyRoo]

Theory meets reality. Pretty sure Honda / Subaru already proved this the hard way.

Started my career in R&D then went to the field. If I had a nickel for every time a R&D guy told me what I was seeing was not possible I would have a coffee can of nickels.

Likely a knife edge of tension doesn’t work as intended. It’s overall force.

I’d personally say there’s way more evidence that Toyota figured out the hard way first. There were a couple different engine models that ended up packing the oil control ring full of gorilla snot and burning oil like it was designed that way.

Don’t know much about the Hondas that do this, but Subaru oil-burning was pretty much limited to one model year, and only the manual transmission vehicles at that. IIRC it was ‘13 Foresters, their first year of the FB25.

Edit: I reviewed. First 3 years of the FB25, so Outback and Forester.

 

[ChrisD46]

Rislone Engine Treatment was the Nostradamus of stuck oil rings before it became a thing - now we have newer products such as Valvoline Restore and Protect, HPL etc. Fans of Mobil 1 ESP 0w30 oil love that high starting oxidation number for a reason .

 

[DirectRejection]

I have yet to observe ANY signs of oil consumption using HPL Premium Plus 0w-8 for numerous 30k mile OCIs.

My driving conditions would be labeled as ideal, as in daily driving and daily 150+ freeway miles.

I posit that the issue is driving conditions and oil design.

 

[SC Maintenance]

I’d personally say there’s way more evidence that Toyota figured out the hard way first. There were a couple different engine models that ended up packing the oil control ring full of gorilla snot and burning oil like it was designed that way.

Don’t know much about the Hondas that do this, but Subaru oil-burning was pretty much limited to one model year, and only the manual transmission vehicles at that. IIRC it was ‘13 Foresters, their first year of the FB25.

Edit: I reviewed. First 3 years of the FB25, so Outback and Forester.

The 2AZ-FE was definitely an oil burner but I don’t think it was a low tension ring design which is the topic of this thread. It pre dates the peak CAFE craziness. I could be wrong, but I think it was other issues.

Low tension rings came into vogue after the step change cafe rules which was around 2010. Which is why I pointed out Honda and subi. They for sure had problems. Others may have also.

 

[ChrisD46]

Do the contents of this paper make you want to alter your oil and oil weight choice as well as OCI length ?

 

[SubieRubyRoo]

The 2AZ-FE was definitely an oil burner but I don’t think it was a low tension ring design which is the topic of this thread. It pre dates the peak CAFE craziness. I could be wrong, but I think it was other issues.

Low tension rings came into vogue after the step change cafe rules which was around 2010. Which is why I pointed out Honda and subi. They for sure had problems. Others may have also.

I’m not really sure either on the date, but it was far before 2010; Ford was using 1.5mm top & 2nd rings on the first year of the 4.6 and that was 1996. The 5.0 which it replaced used 5/64” rings.

Those 2 letters that shall not be mentioned here seems to indicate there’s data that says Toyota began experimenting/moving to low tension rings sometime in the 1980s, which lines up with Ford getting to it by 1996.

 

[MVAR]

Ford was using 1.5mm top & 2nd rings on the first year of the 4.6 and that was 1996. The 5.0 which it replaced used 5/64” rings.

The 4.6 started in 93 with the 1.5, 1.5, 3mm rings. Lincoln MKIII & 94 in the T Bird. Great engines if a bit underpowered. I never experienced ring issues in my old 94 T Bird but sold it at around 175k in 02-03. It saw mainly hwy miles & 3k OCI’s with valvoline syn blend & occasional Mobil 1 so not a rough life.

 

[tired]

The 2AZ-FE was definitely an oil burner but I don’t think it was a low tension ring design which is the topic of this thread

Agree. It was the oil return holes. They changed the design, and the holes were too small. Toyota replaced engines for it.

 

[CR94]

I’m not really sure either on the date, but it was far before 2010; Ford was using 1.5mm top & 2nd rings on the first year of the 4.6 and that was 1996. The 5.0 which it replaced used 5/64” rings.

Those 2 letters that shall not be mentioned here seems to indicate there’s data that says Toyota began experimenting/moving to low tension rings sometime in the 1980s, which lines up with Ford getting to it by 1996.

Mazda's introductory publicity for the 1981 Mazda GLC (which I had, listed below) bragged about the new low-friction (low tension) rings.

 

[SC Maintenance]

I’m not really sure either on the date, but it was far before 2010; Ford was using 1.5mm top & 2nd rings on the first year of the 4.6 and that was 1996. The 5.0 which it replaced used 5/64” rings.

Those 2 letters that shall not be mentioned here seems to indicate there’s data that says Toyota began experimenting/moving to low tension rings sometime in the 1980s, which lines up with Ford getting to it by 1996.

I had a 2002 - 4.6. It didn’t burn any oil at all. I got rid of it at about 175K miles. Just because they were thin doesn’t necessarily mean there low tension I don’t think. The rest of the car fell apart and I think I changed every sensor twice however.

 

[Faawrenchbndr]

This whole deal was one big ball of wax.
There are more than a few components that have led to this overall issue about rings sticking and ring deposits.

It’s not just oil. It’s oil change interval. It’s driving style and conditions. It’s low tension rings. It’s GDI. It’s lack of port injection for the most part.

Most, vehicles should really fall into a severe service category. It’s argued, it’s debated, but it is what it is. The manufacturers pushing these longer oil, change intervals, is my belief the culprit of most of this crap.

A few years, good oil, quality fuel, service the engine at a reasonable interval there will be no issues.

 

[demarpaint]

This whole deal was one big ball of wax.
There are more than a few components that have led to this overall issue about rings sticking and ring deposits.

It’s not just oil. It’s oil change interval. It’s driving style and conditions. It’s low tension rings. It’s GDI. It’s lack of port injection for the most part.

Most, vehicles should really fall into a severe service category. It’s argued, it’s debated, but it is what it is. The manufacturers pushing these longer oil, change intervals, is my belief the culprit of most of this crap.

A few years, good oil, quality fuel, service the engine at a reasonable interval there will be no issues.

I agree with everything you mentioned with one exception, the last sentence. I would change the words "no issues" to "a lot less issues." Things can sometimes go bad no matter how well you service an engine. However you can lessen your problems a lot by not looking to push every mile out of your oil by stretching the OCI to get the perceived maximum ROI from paying for a premium oil. JMO

FTR shortening the OCI of a premium oil might be the winning ticket for some.

 

[ltslimjim]

This whole deal was one big ball of wax.
There are more than a few components that have led to this overall issue about rings sticking and ring deposits.

It’s not just oil. It’s oil change interval. It’s driving style and conditions. It’s low tension rings. It’s GDI. It’s lack of port injection for the most part.

Most, vehicles should really fall into a severe service category. It’s argued, it’s debated, but it is what it is. The manufacturers pushing these longer oil, change intervals, is my belief the culprit of most of this crap.

A few years, good oil, quality fuel, service the engine at a reasonable interval there will be no issues.

I agree with everything you mentioned with one exception, the last sentence. I would change the words "no issues" to "a lot less issues." Things can sometimes go bad no matter how well you service an engine. However you can lessen your problems a lot by not looking to push every mile out of your oil by stretching the OCI to get the perceived maximum ROI from paying for a premium oil. JMO

FTR shortening the OCI of a premium oil might be the winning ticket for some.

Solid points for sake of the argument, but I’ll highlight the need for nuance and case by case basis for blanket statements as @demarpaint expounded on in their reply.

We need to 1) define reasonable interval length and 2) what actually a “premium” oil is.

We know for a fact it still happens on engines that did not extend the interval. Some engines simply have a flaw that even the best oils will need a relatively short interval.

@Glenda W. ’s well documented issue driving their Outback in severe service while keeping the interval to 5k miles on one of Valvoline’s flagship oils at the time; pre- Valvoline Restore and Protect, is one example of why the blanket statement of “there will be no issues” is simply untrue.

There is indeed a point on interval length, but it can’t be singled out as we have seen. I think the early part of the post is on the right track, and defining a true top shelf oil that resists deposit formation in the first place; boutiques or others that have this proven track record, do come into focus. For some, Valvoline’s Valvoline Restore and Protect may be perfectly adequate for those keeping the intervals to 3k in a consumption developing prone engine; whereas a boutique for 7.5k could be another approach. Again, depends on other factors, but if we’re generalizing we still must recognize the oil differences are as much a part of this reality as interval length. It really does matter the oil choice.

Of the primary factors…1) Length of interval relative to conditions, 2) high end oil used, and 3) engine temperament to developing consumption based on design flaws; as all all part of this soup.

^The owner really only controls the first 2 variables. If one owns such an engine, controlling those variables is; to both of your points, the best CoA.

 

[SC Maintenance]

Solid points for sake of the argument, but I’ll highlight the need for nuance and case by case basis for blanket statements as @demarpaint expounded on in their reply.

We need to 1) define reasonable interval length and 2) what actually a “premium” oil is.

We know for a fact it still happens on engines that did not extend the interval. Some engines simply have a flaw that even the best oils will need a relatively short interval.

@Glenda W. ’s well documented issue driving their Outback in severe service while keeping the interval to 5k miles on one of Valvoline’s flagship oils at the time; pre- Valvoline Restore and Protect, is one example of why the blanket statement of “there will be no issues” is simply untrue.

There is indeed a point on interval length, but it can’t be singled out as we have seen. I think the early part of the post is on the right track, and defining a true top shelf oil that resists deposit formation in the first place; boutiques or others that have this proven track record, do come into focus. For some, Valvoline’s Valvoline Restore and Protect may be perfectly adequate for those keeping the intervals to 3k in a consumption developing prone engine; whereas a boutique for 7.5k could be another approach. Again, depends on other factors, but if we’re generalizing we still must recognize the oil differences are as much a part of this reality as interval length. It really does matter the oil choice.

Of the primary factors…1) Length of interval relative to conditions, 2) high end oil used, and 3)engine temperament to developing consumption based on design flaws; as are all part of this soup. The owner really only controls the first 2 variables. If one owns such an engine, controlling those variables is; to both of your points, the best CoA.

I am a short OCI guy myself - but some engines use oil from the day there built. Short OCI won’t overcome lousy design. It might not make it worse best case.

 

[KEVINK0000]

Yes and no. It's not just low tension rings, it's shorter pistons with shorter crowns, which push the ring pack up toward the chamber, increasing their exposure to heat, while the piston itself is a smaller heatsink. The ring pack itself is often shorter as well, again, providing less space within to sink the heat, so you end up with a lower profile band that's exposed to more heat while simultaneously using thinner lubricants with bases that are more apt to degrade in the presence of that heat and leave deposits.

As I've stated before, low tension rings have been in use for at least 30 years. They are not the reason we are now seeing elevated oil consumption and stuck rings, they are just an easy target for people to blame. There are numerous engines that feature them that do not have these issues, it's a culmination of design choices that ultimately gets you there, most of them made to reduce friction and improve efficiency.

And recommended OCIs generally longer than ever, with automated alerts for the owner being the sole source of OCI for most vehicles on the road. That’s been less than a decade in widespread usage.

 

[KEVINK0000]

“Low tension “ 20-30 years ago is different than “low tension” today. The low got lower.

 

[GW.]

Solid points for sake of the argument, but I’ll highlight the need for nuance and case by case basis for blanket statements as @demarpaint expounded on in their reply.

We need to 1) define reasonable interval length and 2) what actually a “premium” oil is.

We know for a fact it still happens on engines that did not extend the interval. Some engines simply have a flaw that even the best oils will need a relatively short interval.

@Glenda W. ’s well documented issue driving their Outback in severe service while keeping the interval to 5k miles on one of Valvoline’s flagship oils at the time; pre- Valvoline Restore and Protect, is one example of why the blanket statement of “there will be no issues” is simply untrue.

There is indeed a point on interval length, but it can’t be singled out as we have seen. I think the early part of the post is on the right track, and defining a true top shelf oil that resists deposit formation in the first place; boutiques or others that have this proven track record, do come into focus. For some, Valvoline’s Valvoline Restore and Protect may be perfectly adequate for those keeping the intervals to 3k in a consumption developing prone engine; whereas a boutique for 7.5k could be another approach. Again, depends on other factors, but if we’re generalizing we still must recognize the oil differences are as much a part of this reality as interval length. It really does matter the oil choice.

Of the primary factors…1) Length of interval relative to conditions, 2) high end oil used, and 3) engine temperament to developing consumption based on design flaws; as all all part of this soup.

^The owner really only controls the first 2 variables. If one owns such an engine, controlling those variables is; to both of your points, the best CoA.

Yes. Both Valvoline and HPL have mentioned piston deposits start right away. So shortening oci length can not stop piston deposits but can control other types of deposits.