Low tension rings

[Titan]

I read many comments stating "low-tension rings" are responsible for oil consumption. But my 2018 Dynamic Force Toyota engine has low-tension rings and stays right on the Full mark on the dipstick, even when I ran it 11,000 miles during an OCI (HPL 0w-20). (I usually only run it about 5000 miles per OCI.) It has over 110,000 miles on it. During one full combustion/exhaust cycle, the rings are moving downward without positive cylinder gas pressure only 1/2 of the time (the other 1/2 is during the power stroke when the exhaust gases are applying significant pressure behind the rings to push the rings out against the cylinder wall). On the upward strokes, there's little to no oil to be scraped off the cylinder walls after a power stroke because the gas pressure scraping force as well as the heat during the power stroke could burn any oil remaining on the cylinder wall. Maybe the best chance for oil to leak by the rings is due to negative pressure generated during the downward intake stroke. (In a turbocharged engine under boost, the intake stroke may not be producing any negative pressure inside the cylinder...but this engine isn't turbocharged.) So, whatever the reason(s) for oil consumption in some engines, I'm not seeing this engine's low-tension rings to result in oil loss.

 

[Cujet]

Low tension rings can work just fine. As always, the precision of manufacturing, piston design, cylinder stability and material wear rates all play a role. The better manufacturers have worked through the issues quite well.

However, many of us are quite aware of the Honda/Acura low tension ring issue, where they were fine right up until the ring end gap increased by exactly 0.002 inches (a very tiny amount of wear) and then the oil consumption was intolerable. The solution is simple enough, install new rings with slightly more tension. The cylinder walls were perfect in just about every case.

 

[Just a civilian pilot]

Low tension rings can work just fine. As always, the precision of manufacturing, piston design, cylinder stability and material wear rates all play a role. The better manufacturers have worked through the issues quite well.

However, many of us are quite aware of the Honda/Acura low tension ring issue, where they were fine right up until the ring end gap increased by exactly 0.002 inches (a very tiny amount of wear) and then the oil consumption was intolerable. The solution is simple enough, install new rings with slightly more tension. The cylinder walls were perfect in just about every case.

Sounds like my Honda Fit.

 

[CR94]

Much the same is also true of my Prius, which doesn't drink much oil. More than a few other owners of similar vintage Prii have complained of heavy oil consumption at roughly similar mileage. Ring sticking may be a factor, besides the wear mentioned by Cujet.

When my '81 Mazda was a new model, Mazda publicity bragged about its reduced ring friction. It always consumed considerably more oil than the Prius, but never got much worse, and lasted ok (see signature below).

 

[The Critic]

One of my friends had a 18, it starting drinking oil on 10K OCI’s with M1 0W16 once it got closer to 100K.

 

[Titan]

However, many of us are quite aware of the Honda/Acura low tension ring issue, where they were fine right up until the ring end gap increased by exactly 0.002 inches (a very tiny amount of wear) and then the oil consumption was intolerable.

So the low-tension can be fine until suddenly it's not. Interesting. Thanks!

 

[Titan]

When my '81 Mazda was a new model, Mazda publicity bragged about its reduced ring friction. It always consumed considerably more oil than the Prius, but never got much worse, and lasted ok (see signature below).

Over 600,000 miles on your Mazda? Yeah...I'd say it "lasted OK"!

 

[doublebase]

So the low-tension can be fine until suddenly it's not. Interesting. Thanks!

That’s been my experience, yes. Everything is just A OK until all the sudden, uh oh. For me it’s been around 115,000-120,00 miles, then boom.

But that doesn’t mean it’s going to be that way for you or anyone else, but oil burners are a thing, and unfortunately rings have played a roll in it. Along with direct injection blasting soot/carbon/fuel into the lands and grooves. Rings can’t seem to force their way out of the grooves, and then the oil control rings become clogged up. I think there’s a number of factors at play, and I’m not saying everyone will experience it on every brand/engine/maintenance routine/oil. But it happens, I think sometimes you can prevent it, sometimes not so much. Just my opinion.

 

[SC Maintenance]

"low tension" doesn't really mean much. Its an adjective.

If the tension was lowered by some amount, but still above the physics of what is needed, then they can be "lower" than traditional, but can still work fine.

Also, lowering the tension on the compression rings, but retaining tension on the oil rings, can provide the frictional savings desired while not causing an oil burner.

As mentioned, there are a lot of other factors in play also, like overall design and part quality. Still I don't see a ton of these new engines going to 400K miles easily like engines from 20 years ago seem to. But not many people ever get there anyway.

 

[OVERKILL]

"low tension" doesn't really mean much. Its an adjective.

If the tension was lowered by some amount, but still above the physics of what is needed, then they can be "lower" than traditional, but can still work fine.

Also, lowering the tension on the compression rings, but retaining tension on the oil rings, can provide the frictional savings desired while not causing an oil burner.

As mentioned, there are a lot of other factors in play also, like overall design and part quality. Still I don't see a ton of these new engines going to 400K miles easily like engines from 20 years ago seem to. But not many people ever get there anyway.

Yep, it's just the latest boogeyman/scapegoat. Ford went to low(er) tension rings for the 302 HO for 1990 IIRC, they were not known to drink oil. If you look back through history you can find many references going back almost 40 years.

 

[buster]

One of my friends had a 18, it starting drinking oil on 10K OCI’s with M1 0W16 once it got closer to 100K.

I'd like to know if it was due to the rings getting carbon buildup.

 

[CR94]

Yep, it's just the latest boogeyman/scapegoat. Ford went to low(er) tension rings for the 302 HO for 1990 IIRC, they were not known to drink oil. If you look back through history you can find many references going back almost 40 years.

More than 40 years. The example I cited in post #4 goes back over 43 years, and I doubt Mazda was the very first. Specifically, the slick brochure in their model-introductory press kit of Fall 1980 claimed engine friction reduction via, among other measures, "Reduced spring tension of piston rings," and "Reduced width of compression rings."

 

[nicholas]

Low tension rings can work just fine. As always, the precision of manufacturing, piston design, cylinder stability and material wear rates all play a role. The better manufacturers have worked through the issues quite well.

However, many of us are quite aware of the Honda/Acura low tension ring issue, where they were fine right up until the ring end gap increased by exactly 0.002 inches (a very tiny amount of wear) and then the oil consumption was intolerable. The solution is simple enough, install new rings with slightly more tension. The cylinder walls were perfect in just about every case.

Would a 30 weight not help in this regard?
Especially in high ambient heat and high load.

 

[Just a civilian pilot]

I'd like to know if it was due to the rings getting carbon buildup.

Wouldn’t HPL clean them up if that was the problem?

Thats the oil I have in the engine right now. I was running Amsoil SS 0w30 since day one but wanted to see if HPL would help.

HPL has been in the engine for over 25,000 miles ( 2 oil changes ) but it still consumes the same amount of oil.

137,000 miles on the car.

 

[buster]

Wouldn’t HPL clean them up if that was the problem?

Thats the oil I have in the engine right now. I was running Amsoil SS 0w30 since day one but wanted to see if HPL would help.

HPL has been in the engine for over 25,000 miles ( 2 oil changes ) but it still consumes the same amount of oil.

137,000 miles on the car.

If you run a high quality oil like Amsoil SS or M1 it's unlikely the rings will be dirty unless you wen too far on the drain interval. But yes HPL would clean any existing deposits up very well.

Oil consumption can also just be from wear and have nothing to do with carbon buildup.

 

[millerbl00]

low tension rings and 10000 plus oil changes is where the problem can start.... Rings get coked up and stick.

 

[Just a civilian pilot]

If you run a high quality oil like Amsoil SS or M1 it's unlikely the rings will be dirty unless you wen too far on the drain interval. But yes HPL would clean any existing deposits up very well.

Oil consumption can also just be from wear and have nothing to do with carbon buildup.

All oil changes have been done according to the Honda "oil life" maintenance minder based on driving habits.

My Honda Civic ( not GDI ) has over 300,000 miles and oil consumption is imperceptible.

PCV has been changed on all my cars.

I don't use top-tier gas FWIW.

 

[OVERKILL]

Wouldn’t HPL clean them up if that was the problem?

Thats the oil I have in the engine right now. I was running Amsoil SS 0w30 since day one but wanted to see if HPL would help.

HPL has been in the engine for over 25,000 miles ( 2 oil changes ) but it still consumes the same amount of oil.

137,000 miles on the car.

Yes, if there was something there, the HPL should clean it up. Which HPL product did you go with?

 

[Just a civilian pilot]

Yes, if there was something there, the HPL should clean it up. Which HPL product did you go with?

Premium Plus 0w30.

 

[AJAX +]

I was curious why with the engine tech today and oils that are better than even 15 years ago we have 30 YO OCI's and started looking at this. What I found was PCV System vacuum is too low. On my 10 MDX that was suppose to drink oil(as I was told mine would too) but never did. I found Honda and Toyota as well as some others run .2 to .8inH2O, in Europe they run 6. to 8.inH2O. Through the years I was familiar with 1 to 3inHg was the norm for the PCV System. Pull the PCV Valve out of the Valve Cover on a Chevy and put your thumb over it and listen to the idle. Everyone's done it.
What they've done is design into the engine a Catch Can and dropped the vac so low they are releasing the excess pressure but not actively pulling a vacuum on the ring pack. This allows the Blowby to accumulate there. 70% is Fuel HC's but the Carbon is sticky and naturally sticks to the rings. In particular the oil control rings. Blowby is not much to dump in the oil and they got away with it for decades but with the evolution of Low Tension rings, Higher Compression and thinner oils the Blowby became a problem.
I avoided the problem bc I didn't trust a 20 weight and ran a Group IV 30. This will allow the oil to contend with the heat trapped and wash the carbon away(or a lot of it) from the ring pack. This is how you can have a delayed issue bc we all run different oils and you can't compare them to American made cars that run the higher vac. e.g. Ford and Chevy.
I used a HVAC Manometer at the dipstick tube and this is the only way to know what your system is doing. Running Synthetics is a way around the problem but it doesn't fix it. I've corrected mine and expect acceptable OCI's from here on. It all matters how well their Catch Can/Baffling traps the Blowby. The oil companies are making a fortune with these short OCI engines. No DTC's or Emission number(LTFT/STFT) after a 950 mile test burning 0 oil pulling an oversized Dump trailer on location. 2010 MDX 290,9XX miles.

F1 is running 8 to 17inHg with a Dry Sump
5 inHg (2.5psi) crankcase depression is enough to:

* eliminate the need for valve stem seals for drag reduction (assumes heads are vented to crankcase)
* eliminate the need for oil rings on the pistons (or very weak zero-drag oil rings)
* eliminate totally any oil contamination of the combustion chamber (slightest minute trace causes detonation which you must design out or "tune out" with the usual methods that reduce power)
* eliminate compression ring flutter and maintain perfect seal at WOT and near-WOT (assuming intake port tuning is somewhat correct)