Main Reasons for Valvoline R&P Popularity : Extended OCI’s + Low Tension Rings ?

[ChrisD46]

I recently took over oil changes for a relative’s 2017 Kia Sorento 3.3L SUV that has started increased oil consumption . The SUV had normal oil service intervals from Kia using bulk oil / Kia cartridge oil filters at approx. 7,500 mile OCI’s (to show great low cost of ownership) .

Long story short - looking down the fill hole was not very clean and the drained oil had black carbon chunks in it . I filled with M1 5W30 ESP + 1 bottle of Rislone Engine Cleaner (I had both on hand) + a Fram Tough Guard cartridge oil filter … Moving forward , I will switch this Kia SUV over to Valvoline R&P 5W 30 to clean this engine up .

My hypothesis : Longer OCI’s with cheap oil + low tension oil rings now predominantly being used are significant reasons for increased oil consumption and dirty internal engine issues . Moving forward , this Kia 3.3L V-6 with 6.9 qrt. sump will get R&P for a 4K mile / 4 month OCI’s until I can slowly move it up to (maybe) a 5K mile / 6 month OCI - time will tell if I can extend after a couple more OCI’s and a UOA (it’s a Kia / Hyundai engine after all) .

 

[OVERKILL]

I recently took over oil changes for a relative’s 2017 Kia Sorento 3.3L SUV that has started increased oil consumption . The SUV had normal oil service intervals from Kia using bulk oil / Kia cartridge oil filters at approx. 7,500 mile OCI’s (to show great low cost of ownership) .

Long story short - looking down the fill hole was not very clean and the drained oil had black carbon chunks in it . I filled with M1 5W30 ESP + 1 bottle of Rislone Engine Cleaner (I had both on hand) + a Fram Tough Guard cartridge oil filter … Moving forward , I will switch this Kia SUV over to Valvoline R&P 5W 30 to clean this engine up .

My hypothesis : Longer OCI’s with cheap oil + low tension oil rings now predominantly being used are significant reasons for increased oil consumption and dirty internal engine issues . Moving forward , this Kia 3.3L V-6 with 6.9 qrt. sump will get R&P for a 4K mile / 4 month OCI’s until I can slowly move it up to (maybe) a 5K mile / 6 month OCI - time will tell if I can extend after a couple more OCI’s and a UOA (it’s a Kia / Hyundai engine after all) .

I'm very hesitant to blame low tension rings, since their use started in the late 80's and these problems really only emerged with the switch to thin oils and GDI/TGDI.

 

[Jetronic]

The lenght (or lack of it) of the oci has a limited effect on the carbon buildup. it's a process that begins on day 1 and never stops. With some oils, the buildup will be close to zero but with others it goes fast.

Running higher compression (and even boosting the intake air), and with the top piston ring closer to the top, and smaller piston skirts, the whole piston ring land are is running hotter than it was. Often times the coolant is running higher temp aswell.

This isn't caused by low tension rings, but by poor design of pistons with low tension rings. Blowby will increase the oxidation rates even further, but that is a secondary effect after the rings have coked up already.

 

[buster]

Subpar oils in many GDI engines when pushed too far will lead to ring sticking down the line. Better oils (more oxidation resistant/detergents and solvency) keep pistons cleaner. GDI engines putting more fuel into the oil and lower detergents and lack of solvency combined with drain intervals that are arguably too long can lead to problems down the road.

PAO/Ester based oils can mitigate deposit formation very well, so you'll never have carbon in ring area. What makes VRP unique is it can completely remove them and prevent them from forming again.

Consider the temperature in the ring area and oil being exposed to those temps over long durations:

 

[Glenda W.]

The scary part is even approved/licensed oils are causing this on 5k oci’s…

 

[OVERKILL]

The scary part is even approved/licensed oils are causing this on 5k oci’s…

Looking at you TGMO...

 

[Hohn]

The lenght (or lack of it) of the oci has a limited effect on the carbon buildup. it's a process that begins on day 1 and never stops. With some oils, the buildup will be close to zero but with others it goes fast.

Running higher compression (and even boosting the intake air), and with the top piston ring closer to the top, and smaller piston skirts, the whole piston ring land are is running hotter than it was. Often times the coolant is running higher temp aswell.

This isn't caused by low tension rings, but by poor design of pistons with low tension rings. Blowby will increase the oxidation rates even further, but that is a secondary effect after the rings have coked up already.

Emissions rules require moving the top rings up as high as temperature and stress limits allow. There is a strong correlation of top ring “crevice volume” to UHC emissions and of course UHC goes with mpg.

So while they are pushing thinner oils with generally not great NOACK, they are also pushing temperatures in the ring lands and grooves much hotter.

So it’s not so much that more oil is left behind my lower oil ring tension, it’s that the oil residue is more volatile while being exposed to hotter temps.

Hence, lots of deposits in ring grooves.

 

[DriveHard]

Emissions rules require moving the top rings up as high as temperature and stress limits allow. There is a strong correlation of top ring “crevice volume” to UHC emissions and of course UHC goes with mpg.

So while they are pushing thinner oils with generally not great NOACK, they are also pushing temperatures in the ring lands and grooves much hotter.

So it’s not so much that more oil is left behind my lower oil ring tension, it’s that the oil residue is more volatile while being exposed to hotter temps.

Hence, lots of deposits in ring grooves.

Assuming UHC's are referencing unburned hydrocarbons...

I thought HC emissions went DOWN as MPG went up, signifying a more complete combustion cycle. I believe as UHC's go down, and MPG go up, you get an increase in NOx. Am I miss-reading your comment about "UHC goes with MPG"?

 

[Hohn]

Assuming UHC's are referencing unburned hydrocarbons...

I thought HC emissions went DOWN as MPG went up, signifying a more complete combustion cycle. I believe as UHC's go down, and MPG go up, you get an increase in NOx. Am I miss-reading your comment about "UHC goes with MPG"?

You are correct. Top ring lands have reduced clearance volumes to lower UHC which is associated with high mpg.

This is why rings and grooves run hotter.

Higher NOx isn’t caused by higher mpg. They are two effects of the same cause. Rather, higher NOx results from calibrations that are improve mpg. For example, advanced timing increases peak cylinder pressure and flame temperature, good for mpg but raises NOx.

 

[DriveHard]

You are correct. Top ring lands have reduced clearance volumes to lower UHC which is associated with high mpg.

This is why rings and grooves run hotter.

Higher NOx isn’t caused by higher mpg. They are two effects of the same cause. Rather, higher NOx results from calibrations that are improve mpg. For example, advanced timing increases peak cylinder pressure and flame temperature, good for mpg but raises NOx.

We are on the same page...I taught a diesel combustion class for a couple of years. I was just simplifying things with the generic HC vs NOx statement.

 

[CarlB]

My understanding was that "low tension" rings make seal using cylinder pressure and are superior to using the thicker rings of old that experience early onset wear. Static tension is what is "low."

The comments on ring land position are definitely true on Subaru EJ engines. That ringland is prone to cracking and bending (pinching of the ring). Subaru isn't ignorant to how engine design works, but had to meet emissions goals. On street cars there are goals pulling engineers in opposite directions.

 

[Hohn]

My understanding was that "low tension" rings make seal using cylinder pressure and are superior to using the thicker rings of old that experience early onset wear. Static tension is what is "low."

The comments on ring land position are definitely true on Subaru EJ engines. That ringland is prone to cracking and bending (pinching of the ring). Subaru isn't ignorant to how engine design works, but had to meet emissions goals. On street cars there are goals pulling engineers in opposite directions.

They are. They don’t make seal using cylinder pressure, but they are assisted significantly in generating sealing pressure by the combustion pressure.

Thinner rings are almost always better as long as they survive and are stable (no ring flutter).