OVERKILL
$100 Site Donor 2021
IMHO, the problem with IIIH is it's run on a naturally aspirated port injected engine that has no history of ring coking or sticking.
What if "low tension ring" theory is all wrong?
- Thread starter Hohn
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It's a very good test for high temperature piston deposits and oil oxidation. Arguably one of the most stringent tests for that specific criteria. Amsoil scored a 7.7 WPD average back in 2014 or so. They also double the interval to 180 hours. dexos has a WPD average of 5.3 I think.
Too bad we don't get to see Red Line or HPL on the IIIH.
Loaded with VM and high volatility (13%).
When you see Toyota with oil consumption that develops over time, I'd guess the majority are using dealer bulk 0w20 or TGMO at Toyota. How many are going the full OLM? I could see this being an issue as most don't care about oil and want whatever is cheap and fast.
Id love to see AMSOILS result now since the current formula performs 99.9x better than the standard for viscosity increase.It's a very good test for high temperature piston deposits and oil oxidation. Arguably one of the most stringent tests for that specific criteria. Amsoil scored a 7.7 WPD average back in 2014 or so. They also double the interval to 180 hours. dexos has a WPD average of 5.3 I think.
Too bad we don't get to see Red Line or HPL on the IIIH.
I'll answer what I believe, obviously not what is necessarily true or what I can prove or demonstrate.
What I think creates stuck rings is a combination of a couple factors:
1) thinner oils generating more aerosols in the ring pack as blowby occurs (all rings have a tiny bit of leak). Small aerosol particles change temperature much faster (ie respond to combustion heat).
2) Thinner oils allowing localized hot spots through film compromise (per Rudnick)
3) Hotter ring land temperatures with higher power density and emissions/mpg mandates
Piston deposits are a lot like seasoning of a cast iron or carbon steel skillet. It's about heat and polymerization.
There's a great interview that Lubrication Explained did with a lady who was a specialist at Horizon labs on varnish formation and removal.
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What is the "low tension ring" theory anyway? There are low tension compression rings which is fine as combustion pressure seals them anyway. Ring tension on compression rings has very little to no effect because that is not what seals the combustion pressures, ring tension doesn't seal combustion pressure. Combustion pressure does the sealing on the compression ring pack.
The consumption problems come with lower tension oil control rings as combustion pressure has no effect on them at all. They need to be free to move and do their job to scrape the excess oil away on the downstroke obviously. When they get coked up and no longer move free, thats when the real problems with consumption will set in. So when the engine is new and deposit free all is well, down the road if the deposits gets too severe, well you get the picture.
I've read thru all this and the posts people have put up and have to say many people here have lots of good stuff to say, others not so much.
I happen to own two Audis, a 3.0t in a older 2013 A6 and the newer "improved" version 3.0t in a 2018 Q7 which they added a second set of port injectors on top of the direct injection, which will keep the intake valves clean and carbon free and thats great, and of course a change to the piston oil control ring pack to a lower tension version. Other than that, some minor tweaks here and there they are both basically the same engines. Both vehicles have mid 90,000 miles on them. Both have been run on 10,000 mile oil changes using 0w-40 or 5w-40 oil. The early older version with higher tension control rings has never ever used a drop of oil on those 10,000 mile intervals. The newer "improved" version 3.0t Q7 I purchased at 84,000 miles was consuming a quart of oil in just 400 miles before I fixed it with a Berrymans B12 piston soak, BG EPR flush and switched it to the Valvoline Restore and Protect. It now no longer consumes any oil in 5000 intervals and I'll continue to utilize 5w-30 Valvoline Restore and Protect moving forward.
The early engine is not known to consume oil, the newer "improved" version with low tension rings however is notorious for consuming oil once it gets some miles on it, they can start Ive read in as little as 35,000 miles, more often then not its around 75,000 miles. If you continue to run with this high consumption on them they are known to fail and burn the exhaust valves from carbon dislodging, sticking and holding the exhaust valve open.
So knowing these engines are for all intents and purposes the same other than the new one having added the secondary port injection on top of the existing direct injection, and lower tension oil control rings, why would the newer engine be known to consume oil down the road with miles if not for the low tension oil control rings?
IMO the problem absolutely points to the lower tension oil control rings being the problem. Now that said, if the oil was up to the task of keeping things clean enough, the lower tension control rings would be up to the task because obviously if they are not stuck, they control the oil just fine. The problem comes when the oil cant keep the oil control ring lands clean and they stick in their groves and allow the oil past into the combustion chamber, keep in mind all these engines are using Euro oils in them, most are having deals changes with the "Audi approved" 5w40 Castrol Euro dealer supplied oils, but others are doing their own changes using various approved Euro oils. It does'nt matter the oil brand much, most all these newer CREC engines are sticking the oil control rings. The exceptions seem to be the guys that run them hard and surprisingly have "tuned" them from early on. These guys are the only ones who haven't seen the oil consumption problems. So running them hard enough seems to help the effort. Perhaps the Euro oils are too thick for running in them with the older crowd and soccer Moms here in the USA... Maybe the thicker Euro oil is better off running hot with high temps on the Autobahn and doesn't do well in the limited speed limits of USA.
I personally feel the Valvoline Restore and Protect is going to work well in these USA low tension oil control ring applications and not only clean things up enough, but keep them clean for the duration of the engines life. I'll find out as I've now switched everything over to Valvoline Restore and Protect including my older 2013 Audi that has never used a drop of oil. I'll plan to change the Valvoline Restore and Protect at 5000 mile intervals. Hopeful the consumption doesn't come back on the Q7 and the Valvoline Restore and Protect actually works as good as I think it will. So far its looking really promising.
The consumption problems come with lower tension oil control rings as combustion pressure has no effect on them at all. They need to be free to move and do their job to scrape the excess oil away on the downstroke obviously. When they get coked up and no longer move free, thats when the real problems with consumption will set in. So when the engine is new and deposit free all is well, down the road if the deposits gets too severe, well you get the picture.
I've read thru all this and the posts people have put up and have to say many people here have lots of good stuff to say, others not so much.
I happen to own two Audis, a 3.0t in a older 2013 A6 and the newer "improved" version 3.0t in a 2018 Q7 which they added a second set of port injectors on top of the direct injection, which will keep the intake valves clean and carbon free and thats great, and of course a change to the piston oil control ring pack to a lower tension version. Other than that, some minor tweaks here and there they are both basically the same engines. Both vehicles have mid 90,000 miles on them. Both have been run on 10,000 mile oil changes using 0w-40 or 5w-40 oil. The early older version with higher tension control rings has never ever used a drop of oil on those 10,000 mile intervals. The newer "improved" version 3.0t Q7 I purchased at 84,000 miles was consuming a quart of oil in just 400 miles before I fixed it with a Berrymans B12 piston soak, BG EPR flush and switched it to the Valvoline Restore and Protect. It now no longer consumes any oil in 5000 intervals and I'll continue to utilize 5w-30 Valvoline Restore and Protect moving forward.
The early engine is not known to consume oil, the newer "improved" version with low tension rings however is notorious for consuming oil once it gets some miles on it, they can start Ive read in as little as 35,000 miles, more often then not its around 75,000 miles. If you continue to run with this high consumption on them they are known to fail and burn the exhaust valves from carbon dislodging, sticking and holding the exhaust valve open.
So knowing these engines are for all intents and purposes the same other than the new one having added the secondary port injection on top of the existing direct injection, and lower tension oil control rings, why would the newer engine be known to consume oil down the road with miles if not for the low tension oil control rings?
IMO the problem absolutely points to the lower tension oil control rings being the problem. Now that said, if the oil was up to the task of keeping things clean enough, the lower tension control rings would be up to the task because obviously if they are not stuck, they control the oil just fine. The problem comes when the oil cant keep the oil control ring lands clean and they stick in their groves and allow the oil past into the combustion chamber, keep in mind all these engines are using Euro oils in them, most are having deals changes with the "Audi approved" 5w40 Castrol Euro dealer supplied oils, but others are doing their own changes using various approved Euro oils. It does'nt matter the oil brand much, most all these newer CREC engines are sticking the oil control rings. The exceptions seem to be the guys that run them hard and surprisingly have "tuned" them from early on. These guys are the only ones who haven't seen the oil consumption problems. So running them hard enough seems to help the effort. Perhaps the Euro oils are too thick for running in them with the older crowd and soccer Moms here in the USA... Maybe the thicker Euro oil is better off running hot with high temps on the Autobahn and doesn't do well in the limited speed limits of USA.
I personally feel the Valvoline Restore and Protect is going to work well in these USA low tension oil control ring applications and not only clean things up enough, but keep them clean for the duration of the engines life. I'll find out as I've now switched everything over to Valvoline Restore and Protect including my older 2013 Audi that has never used a drop of oil. I'll plan to change the Valvoline Restore and Protect at 5000 mile intervals. Hopeful the consumption doesn't come back on the Q7 and the Valvoline Restore and Protect actually works as good as I think it will. So far its looking really promising.
40 grades meant a HTHS of no less than 3.5. There weren't any 30 grades which met that minimum.
I'm not familiar enough with the Audi products to speak with any authority at all, but it does seem that the idea that they are "the same other than" is quite the leap of faith. Even a relatively small change to something like the surface finish hone of the bores might have a huge effect on the overall tendency to become an oil burner. The could have changed ring surface finish, piston ring suppliers, etc. These are all small changes with outsized potential effect on becoming an oil burner or not.
You'd know more than I would about the relatively body of experience of the customer base for these products. I do think many times Autobahn-capable vehicles driven by grandmotherly types can often have quite difficult problems. Thoroughbreds make terrible draft horses.
OVERKILL
$100 Site Donor 2021
Are we talking about the EA837 and EA839?
If so, this 2016 EA837 video shows an extremely short oil control ring stack (which is plugged with deposits, shocker):
And four tiny 1/3 of a circle drains on the skirt sides:
From this video:
While this EA839 tear-down:
https://www.034motorsport.com/blog/...review-of-root-causes-and-design-limitations/
Shows what appears to be a slightly taller oil control stack, along with two half-circle drain holes (and this piston has cracked), but also a decrease in distance between the 2nd compression ring and the oil control rings:
I'd argue both are pretty awful designs.
Here are some Ford 3.5 Ecoboost pistons in comparison (also with low tension rings):
Note the much larger gap between the 2nd compression ring and the oil control rings and what appears to be a taller oil control ring stack This is a failed engine, and, while not deposit free, the oil control rings look considerably better than the EA837 teardown, despite having much more skirt wear.
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Correct,
There is no mention of differences however in the ring stack moving up or down on the piston on the Audi program where they discuss all changes to the next generation. There is mention of a slight increase in compression from 10.3 to 10.8 with the piston and head chamber, a slightly different piston shape design change, and control ring change to reduce friction, so I assume they mean a lower tension ring there, but like I said thats my assumption, but the verbiage "reduced friction" tells me that makes the most sense.
Another change is the block has also gone to steel sleeves and gone away from the nicasil coating on the block. So yes, bore material is different for sure. The fact remains that with miles on it, the newer engine start to consume oil due to the control rings sticking, and they stick over time when the deposits get severe enough to rear their ugly head. Guys on the AudiWorld forum have claimed to have reversed this but just doing the Valvoline Restore and Protect oil alone, most guys along with myself, have done a more drastic procedure with piston soaks, Yamalube ring free, many engine flushes and the typical things that have helped unstick the rings. So wether the Euro oils just cant keep things clean enough, bad designs, poor oil specs or whatever causes the problems, the old engine doesn't have the pre-mature oil usage issues the new engine does. That said, I have seen consumption issues on older Audis that get up there around 200,000 miles, so does it just take longer possibly? Not certain, but I blame the low tension oil control rings as they are supposed to stay free and wipe the excess oil from the cylinder as the 3.0t engines are very similar sans the oil control rings. IMO the new low tension rings don't have enough tension on them to do their job when the deposits build. I'm not saying other factors could be to blame without more research, but just what I see based on the info I've read online and in Audis mechanical study program.
I understand about moving ring packs up and down on the piston, but that does not seem to be the case here as it is not mentioned that it has been changed, and they do make mention of every little change they have on the study program, no matter how small it could be, they are very thorough. The fact remains, that when new these engines don't consume oil at all, nor do the vehicles driven hard and tuned and run hard or used in the European countries, so that raises another thought that more heat, power and RPM's applied to this engine using higher HTHS Euro oils keep the rings from sticking also. Leads me to believe that the lower speeds run here in the states with less oil temps is pointing to something there at fault possibly too. Is the high HTHS Euro oil too heavy for US and lower RPM usage here causing the issue? Sure could be.
Either way, my hope is that Valvoline Restore and Protect, even though it's not "Euro or Audi approved", will keep them from sticking again. If I get sticking again (which I don't see happening using the Valvoline Restore and Protect), worst case scenario is do another piston soak and more flushing. It seems like the Valvoline Restore and Protect is working well to help this consumption problem on the 3.0t CREC engines.
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Looks just like the guys on the Q7 forum photos of the burned exhaust valves on the CREC 3.0t engines. Carbon chunks break free and hang them open and its burn city just like that. Its been happening all too often when the consumption gets up to that point. It's like playing Russian roulette if you don't unstick the rings with a piston soak or do something more drastic to fix it.
IMO, this is the nature of trying to control 1 variable in a way that has no awareness or concept of the downsides of that 1 move when it has a single metric as a goal (increase the MPG numbers!). Yet, what about the other results of such a decision vs one made in a vacuum; i.e. "read world"? Whether it was knowingly or not, it still goes back to trying to get as low as possible in operating thickness for what purpose? Clearly, improve the MPG, but as we've discussed over and over; what is the cost of such a slight tick of the needle (and, ironically, if you end up with stuck rings there goes some efficiency and possibly an engine; looking at you HyunKia )...
OVERKILL
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Do they mention the change in the size and number of oil drainback holes?
I'm just going by what I'm seeing in the photos, if there is a difference, it's small, but there's also a reduction in the size and number of the oil drainback holes, which is readily visible in the photos.KnappAttak said:
The broader point I'm making is the design issues present here, with both iterations of the pistons, are not present on the pistons from a competitor's engine, who also uses low tension rings, but has a much larger gap between the 2nd compression ring and the oil control rings, and a taller oil control ring stack. Ergo, it's not a "low tension rings" problem, it's a "we put super short low tension rings on a super short piston" problem, that leads to coking and sticking eventually.
Viscosity would have nothing to do with it, if anything lower oil temps would reduce the propensity for deposit formation. You are quite likely right that engines that are flogged, where more pressure is placed on the rings, forcing them to move around, keeps them freer. These are also likely better maintained, as, anecdotally, I tend to see people that intentionally drive hard/race, tend to stay more on top of maintenance than the soccer mom that gets the oil changed when she gets sick of the light on the dash telling her that it's due, and she goes to the dealer or Jiffy Lube.KnappAttak said:
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To me this has always seemed a chicken & egg scenario. I've read that the carbon is a byproduct of incomplete combustion.
I don't see a direct correlation between incomplete combustion, and oil at first.
Once the rings are sticking surely some of the carbon is a byproduct of the oil, entering the combustion process.
Does oxidation cause a loss of cleaning, and sealing, but not a loss of lubrication?
There are so many engines with low tension rings, run their entire lives on 0w-20, (regardless of the injection system installed,) that never have a problem with rings sticking. I have a hard time believing that 0w-20 is the root cause.
Or that moving up to a higher grade is the solution, for those people that do experience the issue.
OVERKILL
$100 Site Donor 2021
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.
There are a number of cases where low tension piston rings lose all tension. This is sometimes heat related, annealing if you will. In those cases 0W-20 high quality oil use was typical. Generally with near zero deposits. Think Honda/Acura and a number of GM and Ford engines. The fix is a simple re-ring and 5W-30 syn. This is separate and distinct from stuck rings and clogged piston drain holes.
Sometimes the intended target is not what we are told, sometimes you have to look at the result, to see the intent. Like I said, incompatibility.
If efficiency was the goal, we had cars in the 80s that got more than today........decrease the HP, remove all the power windows, remove all the creature comforts, carpet, etc. That would increase MPG much much more than some ridiculous emissions systems. Heat, AC, gas pedal, brake pedal, lights horn, done. Leave it up to the aftermarket....like way back in the day.
The evidence shows, that the mission is making us spend more money on cars, more frequently.
Our first family car was my wife's used 92 Civic Hatchback. It was the "VX" edition with the "lean burn" engine; D15Z1. 92 HP but it was a manual and the VTEC kicked in so.
That thing was abused before we ever got it. 35MPG. My Honda Fit averages 30. 
Well, to the credit of todays stuff, if you were to remove all the nonsense, and omnipresent gadgets, and the like, ill bet you would surpass your JDM civic by alot, plus your new Fit likely has more power=big efficiency gainOur first family car was my wife's used 92 Civic Hatchback. It was the "VX" edition with the "lean burn" engine; D15Z1. 92 HP but it was a manual and the VTEC kicked in so.
edit:
if i remember right, my 1990 Infinity V6, m30 (300z) luxury version, got 28 highway, and less way city, and fast. might be misremembering, nearly identical to this one:
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