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

[GW.]

IMO the 90’s were the heyday of efficiency and reliability. Anything from Honda/Toyota, Volvo 850, Buick 3800 series and many more. 300k on conventional 10W-30 or 10W-40. 30+ mpg.

 

[Mechanician]

It's predominantly a design issue, yes.

Don't think about the carbon, it's not relevant. It's the breakdown of the VII polymers and base oils into varnish and lacquer that eventually cause the rings to stick in their grooves. These deposits also neck down the oil return holes and fill up the flow through section of the oil control rings, restricting flow, which in turn reduces the rate of flow through the ring lands, which increases the amount of oxidation and breakdown happening due to a longer dwell time, which further restricts the orifices...etc. It's a vicious cycle.

The propensity for thinner base oils and higher VII content to be more prone to this process doesn't mean that a properly designed piston and ring combination won't avoid it from happening. And, conversely, that a poorly designed piston and ring combination would avoid it through the use of heavier base oil blends and lower VII content, an example of which being the Audi engine discussed in this thread.

So the rings are sticking due to varnish and lacquer, not the carbon.
This brings to mind two more questions.

How does the correlation between low cylinder temperatures, and sticking rings (on VCM engines) come into play?
Are higher temps needed to clean the varnish? Or are VCM engines an outlier?

How does a lower VII oil like 0w-20 compare in the process you describe, to a higher VII oil like 0W-30 or 40?
Might a higher grade oil actually be more harmful?

 

[OVERKILL]

So the rings are sticking due to varnish and lacquer, not the carbon.
This brings to mind two more questions.

Correct, if you've ever taken apart an engine with stuck rings, the material in the lands themselves is a heavy, sticky varnish, which also coats the rings, while the material packed into the centre is more like a lacquer with carbonaceous material embedded in it, and this combination kind of "packs" into that centre belt, which you can see on the Audi pics.

How does the correlation between low cylinder temperatures, and sticking rings (on VCM engines) come into play?

Are we speaking specifically about Honda and the rear bank problem, where the head becomes varnish city and the rings also stick? Because both GM (generally) and Stellantis (not at all) don't have this issue with AFM/MDS. These Honda engines seem particularly prone to producing varnish (the 3.5L).

I don't think it's the low cylinder temperatures, but something that was touched-on earlier in the thread, and that's the action of the combustion gasses on the rings to move them in and out of their grooves, this is not only for ring seal on the compression rings, but also the oil control rings. This isn't happening when VCM is active. So, if you've already got an environment that is prone to producing varnish and lacquer, giving it a spot where it can accumulate isn't going to help things.

Are higher temps needed to clean the varnish? Or are VCM engines an outlier?

No, varnish/lacquer require heat. See my above thoughts on why Honda's VCM engines may be more prone.

How does a lower VII oil like 0w-20 compare in the process you describe, to a higher VII oil like 0W-30 or 40?
Might a higher grade oil actually be more harmful?

Depends on how they are blended, what VII's are being used...etc. A 0W-20 can be blended with extremely thin base oils and lots of VII (TGMO) or with heavier base oils and very little VII (Mobil 1 Extended Performance 0w20 when it was PAO-based). There's no standard way to blend any of these products, so we can't, in clear conscience, generalize to that degree.

 

[Mechanician]

Correct, if you've ever taken apart an engine with stuck rings, the material in the lands themselves is a heavy, sticky varnish, which also coats the rings, while the material packed into the centre is more like a lacquer with carbonaceous material embedded in it, and this combination kind of "packs" into that centre belt, which you can see on the Audi pics.

Yes I've replaced many sets - and always categorized it all as carbon. I can relate to your description.

Are we speaking specifically about Honda and the rear bank problem, where the head becomes varnish city and the rings also stick? Because both GM (generally) and Stellantis (not at all) don't have this issue with AFM/MDS. These Honda engines seem particularly prone to producing varnish (the 3.5L).

Actually it's the front bank head that gets so varnished. I've always figured it was because that's where the PCV valve is located. Whereas the rear head receives the fresh intake air for the system, from before the throttle body and is usually much cleaner.

I don't think it's the low cylinder temperatures, but something that was touched-on earlier in the thread, and that's the action of the combustion gasses on the rings to move them in and out of their grooves, this is not only for ring seal on the compression rings, but also the oil control rings. This isn't happening when VCM is active. So, if you've already got an environment that is prone to producing varnish and lacquer, giving it a spot where it can accumulate isn't going to help things.

The term I've read is the cylinders become "air springs", I would imagine that would exercise the rings quite well. But I've also read that during the vacuum cycle the cylinders pull oil in past the rings. Which I guess could start the vicious cycle mentioned earlier.

No, varnish/lacquer require heat. See my above thoughts on why Honda's VCM engines may be more prone.

Depends on how they are blended, what VII's are being used...etc. A 0W-20 can be blended with extremely thin base oils and lots of VII (TGMO) or with heavier base oils and very little VII (Mobil 1 Extended Performance 0w20 when it was PAO-based). There's no standard way to blend any of these products, so we can't, in clear conscience, generalize to that degree.

So I assume blaming the problem on a specific viscosity, or claiming a different viscosity is the solution, would be generalizing too much as well.

 

[OVERKILL]

Yes I've replaced many sets - and always categorized it all as carbon. I can relate to your description.

Actually it's the front bank head that gets so varnished. I've always figured it was because that's where the PCV valve is located. Whereas the rear head receives the fresh intake air for the system, from before the throttle body and is usually much cleaner.

Sorry, my mix-up, thought it was the rear for some reason (which would run hotter), might be thinking of another engine? I know @Trav has written about his (numerous) experiences with this engine so it would seem to be a Honda-specific issue (VCM + ring sticking).

The term I've read is the cylinders become "air springs", I would imagine that would exercise the rings quite well. But I've also read that during the vacuum cycle the cylinders pull oil in past the rings. Which I guess could start the vicious cycle mentioned earlier.

There'd be very little in the way of pressure put on the rings from just acting on the air that's there vs the tremendous force generated by combustion. Yes, vacuum would probably not be ideal, but that would only become a potential problem when the cylinder reactivates and the oil that's migrated to places it is perhaps not supposed to go, gets cooked. But other engines with cylinder deactivation, as I mentioned, don't suffer this issue, so there are clearly factors in play.

So I assume blaming the problem on a specific viscosity, or claiming a different viscosity is the solution, would be generalizing too much as well.

Correct. As I said earlier, you aren't fixing a mechanical problem with an oil. While oil selection can exasperate, or mask, underlying issues, they are ultimately still there.

 

[TiGeo]

Recent post that a LSJR video link was posted where he discusses oil consumption related to low tension rings:

Thread 'LSJR on oil consumption' https://bobistheoilguy.com/forums/threads/lsjr-on-oil-consumption.400244/

 

[Kernel Potter]

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.

So let me get this striaght; If one were to use HPL Euro Passanger Car 0w-20 in a new turbocharged vehicle, like say a 1.4GDI VW Jetta, the oil and thus the engine will fail and fairly quickly. It's just a matter of time until the rings are gunked up and not functioning correctly. On top of that there will be excessive bearing wear and the engine will see a short life. Hopefully not before getting out of VWs warranty period.

But..... if you simply use HPL Euro Passenger Car 5w-40 instead of 0w-20 then disregard everything said above. The engine will now last hundreds and hundreds of thousands of wear free miles. No gunked up rings and oil consumption, no receded valves, no catastrophic bearing wear.

Which begs the question. How could a lubricant company survive - with a good reputation no less, selling 20 weight or lower viscosities?

 

[goblin]

...
Which begs the question. How could a lubricant company survive - with a good reputation no less, selling 20 weight or lower viscosities?

Well now, Sir, it is quite clear - the smart ones simply only sell 5w40, and repackage it accordingly. Duh !!!

 

[JunkdrawerDog]

IMO the 90’s were the heyday of efficiency and reliability. Anything from Honda/Toyota, Volvo 850, Buick 3800 series and many more. 300k on conventional 10W-30 or 10W-40. 30+ mpg.

The wife and I bought a new Civic in 1987 and another in 1993. Both engines were flawless for over 150k miles with little to no oil consumption. Both were dealer serviced at ~4000 mile intervals on 10w-30 conventional.

 

[Hohn]

So let me get this striaght; If one were to use HPL Euro Passanger Car 0w-20 in a new turbocharged vehicle, like say a 1.4GDI VW Jetta, the oil and thus the engine will fail and fairly quickly. It's just a matter of time until the rings are gunked up and not functioning correctly. On top of that there will be excessive bearing wear and the engine will see a short life. Hopefully not before getting out of VWs warranty period.

But..... if you simply use HPL Euro Passenger Car 5w-40 instead of 0w-20 then disregard everything said above. The engine will now last hundreds and hundreds of thousands of wear free miles. No gunked up rings and oil consumption, no receded valves, no catastrophic bearing wear.

Which begs the question. How could a lubricant company survive - with a good reputation no less, selling 20 weight or lower viscosities?

You know that’s not true and shame on you for pot stirring. Find another thread.

 

[TiGeo]

The wife and I bought a new Civic in 1987 and another in 1993. Both engines were flawless for over 150k miles with little to no oil consumption. Both were dealer serviced at ~4000 mile intervals on 10w-30 conventional.

And a bazillion folks have bought cars in the last 10 years running 20 grade with the same results.

 

[Jetronic]

And a bazillion folks have bought cars in the last 10 years running 20 grade with the same results.

and a gazillion bazillion didn't have the same result.

 

[TiGeo]

and a gazillion bazillion didn't have the same result.

Yes, indicating that there is in fact more than one variable to engine longevity than the singular get-off-my-lawn crew's oil grade variable.

 

[Hohn]

It’s worth refreshing the point that the “perfect” viscosity is not only duty cycle dependent, but also that “ideal” and “sufficient” can be far apart. It’s possible that thicker is better and yet it’s the difference between 400k and 650k miles for tte same amount of wear. Let’s not distort the argument to be something it isn’t. It’s quite likely that some engines prone to become burners earlier need much thicker than recommended oil. It’s also possible that others that aren’t prone to such would last long on thicker oil, though the difference is irrelevant for most users who will never keep the vehicle long enough. It’s also possible that due to design issues, no oil can prevent an engine from becoming a burner.

It’s hardly controversial to recognize that empirical testing shows lower wear with higher hths oils. It’s up to the user to decide if their application will benefit from that enough to offset potential mpg penalties.

 

[goblin]

My unscientific take is - find the owner manual specific to your engine for a vehicle with this engine sold on a market that is considered severe usage all-around. Somewhere in Africa for example.
This might be an issue as the manufacturer might not have an official presence there, but it's doable.
See what viscosity they recommend. That's the "real" viscosity your engine was made for.
Compare more countries if possible. See if the manual recommends different viscosity for different markets.

 

[TiGeo]

My unscientific take is - find the owner manual specific to your engine for a vehicle with this engine sold on a market that is considered severe usage all-around. Somewhere in Africa for example.
This might be an issue as the manufacturer might not have an official presence there, but it's doable.
See what viscosity they recommend. That's the "real" viscosity your engine was made for.
Compare more countries if possible. See if the manual recommends different viscosity for different markets.

The ol' "look in owner's manuals in other countries"...a classic on my BITOG Bingo thick/thin card.

 

[ripcord]

The oils today are better than 95% of the oils from the "high tension" ring days. So I don't understand why ring belt oxidization wouldn't have been a big issue back then.

I think it was. When I was a teen I helped my uncle do a ring job in his shop on an LTD with a 390. Most of the rings were stuck in their grooves with carbon. After I removed the rings and de-carboned the pistons, we could have probably put the old rings back in and it would have fixed the oil burning.

 

[Mainia]

I would think the off-shelf API EP oils and Valvoline Restore and Protect would keep rings from sticking under OE drains more so then dealer bulk 0w20, some of which have Noack of 13%. Go up further to Euro as well. I'd be curious how many of the ring sticking issues were ran on low cost bulk 0w20's with Noack near 14% and a ton of cheap VM.

Not mine, no cheap oils and longer oil change dumps then 3,000 miles. But I think I am an outlier. Could be my very high top/second ring temps being on full boost a lot of the time. AND being a Hyundai/Kia of course.

 

[Kernel Potter]

You know that’s not true and shame on you for pot stirring. Find another thread.

Stirring the pot? Your original post shows quite clearly that lower hths oils cause higher levels of carbon build-up, ring glazing, acid and varnish formation and higher temperatures raising oxidation. It's says nothing about the right viscosity for the application.

I gave an example that if this it true, then anyone selling low hths oil will have a PR disaster on their hands, which they don't. Let alone the 100s of millions of engine owners using low hths oils who are going to have disasterous results, which they don't.

It's simple and logically to the point. If you don't get your way don't tell me I'm stirring the pot. Closing the thread would be better alternative.

 

[SubieRubyRoo]

Thinner rings run hotter. Hotter oil oxidizes faster. Oxidized oil kept at high temps first turns to a sticky mess, and then as that sticky mess continues to cook off volatiles, it becomes a hard encrustation. Reducing overall detergent levels isn’t helping one bit, as this allows surface agglomeration to accelerate. Tack on 10k OCIs for the appearance of “reduced maintenance vehicles” and it’s a perfect recipe to deliver stuck rings.

Low tension rings “may” let a touch more oil through, but lower tension combined with thinner ring packs means there just isn’t anywhere the same conduction from the (really) hot pistons and rings into the (relatively) cool cylinder walls.

That’s my take. Might be partially incomplete or totally incorrect.