Carbon Build-Up in Piston Rings

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222
Location
Fort Erie, ON
From what I've learned so far, many oil-burning engines burn oil because of seized rings due to carbon build-up in the ring grooves. The Saturn SL series 1.9L engine seems to be one engine prone to this problem. How hot do the ring grooves have to get before oil starts to carbonize? Would more frequent OCIs avoid this problem or does it happen with fresh oil as soon as the pistons become hot enough?
 
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3,756
Location
CA
I may be wrong but I believe the less VIIs the oil has, the less of a problem you'll have with this.
 
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1,385
Location
Houston, TX
With Saturn, it's a design issue, especially if this is a pre-98 engine. There is a TSB on a decent method of how to clean them out and then continue to clean, helped my wife's car quite a bit with consumption and smoking. Cliff Notes-- remove spark plugs, pour Berryman's B-12/Chemtool into the cylinders, let sit over night. Soak up/suck out anything left in there the next day, reinstall plugs, change oil to "Mobil 1 5w-30" per the TSB but really any good oil should do. We tried Auto-RX and it helped a bit, but you really had to keep up with the maintenance doses or the rings got stuck pretty much right away. This car had 160K miles IIRC when we sold it. Oh, and ONLY use the Saturn PCV valve, all others don't have the correct pressure spec.
 
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25,041
Location
ON, Canada eh?
Also lack of maintenance or too long of OCI, lower quality oils can cause this. Some engines are more prone to it than others... Use a quality oil/filter, change at the manuals reccomended OCI or sooner and do an Auto-RX, or other cleaning treatment once/while and you will be good!
 

PT1

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5,746
Location
near the mistake
 Originally Posted By: Solo2driver
With Saturn, it's a design issue, especially if this is a pre-98 engine. There is a TSB on a decent method of how to clean them out and then continue to clean, helped my wife's car quite a bit with consumption and smoking. Cliff Notes-- remove spark plugs, pour Berryman's B-12/Chemtool into the cylinders, let sit over night. Soak up/suck out anything left in there the next day, reinstall plugs, change oil to "Mobil 1 5w-30" per the TSB but really any good oil should do. We tried Auto-RX and it helped a bit, but you really had to keep up with the maintenance doses or the rings got stuck pretty much right away. This car had 160K miles IIRC when we sold it. Oh, and ONLY use the Saturn PCV valve, all others don't have the correct pressure spec.
I went through this with my 2006 GMC 6.0L piston knocker. It worked for 5000 miles and then was knocking worse after that. GM is famous for this issue with many engines. This engine did this after 20,000 miles of PP and 5000 OCI's with the first OCI at 1,000 so it got 5 oil changes with PP 5w30 and still knocked.
 
Last edited:

fraso

Thread starter
Messages
222
Location
Fort Erie, ON
I understand that there are ways to fix a stuck ring problem in a Saturn. I am more interested in the mechanism in which the rings become carbonized in the first place. It's really a general question about any car -- not just Saturns. Does anyone know how hot the ring grooves have to get for this to happen? I tried searching the forum already but did find this answer yet.
 
Messages
3,756
Location
CA
 Originally Posted By: fraso
I understand that there are ways to fix a stuck ring problem in a Saturn. I am more interested in the mechanism in which the rings become carbonized in the first place. It's really a general question about any car -- not just Saturns. Does anyone know how hot the ring grooves have to get for this to happen? I tried searching the forum already but did find this answer yet.
Don't know the temp but I'm pretty sure VIIs play a large role in the deposits.
 
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827
Location
Iowa
The 1.9 Saturn motor twin-cam, 4 valve engine is famous for bad valve guides and seals, causing high oil consumption. Of course eventually this could also cause stuck rings. You have been given good advice so far, avoid high VI additive oils (10W40 was banned in GM vehicles years ago for this issue). As a survivor of one of these, my advice: Buy cheap oil, add as needed, ignore it. Our Saturn burned oil from 80K miles to past 200 k and still ran fine. If it burned 120 qts of oil during that time, it only cost 150 bucks or so to keep it topped up.
 
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1,034
Location
GA, USA
Our Olds Intrigue w/ the 3.5L "Shortstar" V6 is prone to this type of oil consumption, as are Northstar engines in general. I initially used M1 5W-30 but it would consume it at a pretty fast rate (>1 qt/OCI). I switched to GC (0W-30) and oil consumption has decreased dramatically (virtually none, I don't have to top off). I A-Rx'ed the engine prior to the switch to GC and I run a qt. of 5 min. engine flush at every oil change. I add 6 oz. LC-20 (6 qt. oil capacity) to the fresh oil. I've also PowerFoamed the intake a couple times in the 105K miles we've put on the car since new and we run Shell (top tier) regular exclusively. The car runs perfectly and typically returns 22 mpg in mixed driving (probably would be higher if it had another cog in the trans but that's another story). As has been mentioned, some engine designs are more prone to ring pack deposits and consequently higher oil consumption than others and I'm convinced Northstar based engines are included. I think the combination of a high viscosity synthetic 0W-30 (probably with a low amount of VII), LC-20, engine flushes, decent quality fuel and possibly the occasional PF has kept the top end and ring packs clean. We plan on keeping the car for many more years and miles and this regimen seems to be working to keep the engine running well. YMMV
 
Messages
6,388
Location
Washington St.
Visualize a piston inside a cylinder. There is a small "pocket" of space around the piston above the top ring and below the crown of the piston. The pocket holds some fuel/air mixture that doesn't burn well. If the size of the pocket is reduced the emissions are cleaner with no added cost or effort. But...but putting the ring higher up on the piston means that it runs hotter. A hotter piston ring bakes the oil into carbon more readily, sticks in the ring groove, and all the other well known problems. Not one of GM's better engineering moves.
 

fraso

Thread starter
Messages
222
Location
Fort Erie, ON
Thanks for the responses so far. It sounds to me that the oil will start to bake as soon as the piston gets hot enough. A shorter OCI would therefore not help the carbonizing situation. A synthetic oil would be offer more protection in this case. Does anyone know how hot the ring groove would have to be for (conventional?) oil to carbonize?
 
Messages
19,683
Location
Sunny Florida
Hot enough to burn the oil. BTW, almost every engine on the road will be or already has shifted that top ring closer and closer to the piston crown. You almost have to to meet emission standards. This also occurs most often in engines that have been babied during break in. More blow by is a coker for sure. And somebody tell the poor GMC owner that the piston slap is a non-issue. You can run those engines 300-400 thousand miles all the while hearing the knock. I have more than one of these, they will run almost forever!
 
Messages
441
Location
Bismarck, ND
 Originally Posted By: PT1
 Originally Posted By: Solo2driver
With Saturn, it's a design issue, especially if this is a pre-98 engine. There is a TSB on a decent method of how to clean them out and then continue to clean, helped my wife's car quite a bit with consumption and smoking. Cliff Notes-- remove spark plugs, pour Berryman's B-12/Chemtool into the cylinders, let sit over night. Soak up/suck out anything left in there the next day, reinstall plugs, change oil to "Mobil 1 5w-30" per the TSB but really any good oil should do. We tried Auto-RX and it helped a bit, but you really had to keep up with the maintenance doses or the rings got stuck pretty much right away. This car had 160K miles IIRC when we sold it. Oh, and ONLY use the Saturn PCV valve, all others don't have the correct pressure spec.
I went through this with my 2006 GMC 6.0L piston knocker. It worked for 5000 miles and then was knocking worse after that. GM is famous for this issue with many engines. This engine did this after 20,000 miles of PP and 5000 OCI's with the first OCI at 1,000 so it got 5 oil changes with PP 5w30 and still knocked.
Same here with my 8.1. i just use 5-30 mobil 1. i seems to be the best at keeping the knock to a minimum. oh i do also run MMO for 500 miles every 6-10k miles
 
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1,714
Location
CA.
 Originally Posted By: Petrou
oh i do also run MMO for 500 miles every 6-10k miles
It certainly won't hurt anything. AD
 
Messages
19,479
Location
Chicago Area
The fresher the oil, the better off we are in this area [rings/lands]. Also, some oils carbonize at lower temps, and have different additive packs. If your rings are already stuck, a products called Auto Rx can help a lot. Follow their regimen - it takes a few thousand miles, but works.
 

fraso

Thread starter
Messages
222
Location
Fort Erie, ON
This is general question. Besides the Saturn issue I am aware of, one of our ACCCC members has 1964 Rover Sedan (3.0L) that had stuck rings when he first got it. I believe he used a ring solvent to free them up. Basically, I am interested to know how to prevent the rings from getting stuck in the grooves in the first place. My guess is that most people with stuck-ring Saturns (along with other GMs and Rovers) used conventional oil (Group II?). The Rover probably used Group I previous to the current owner. Are there any Group II oils resistant to the high temperatures as found in piston ring grooves? If not, would any Group III oil be resistant?
 
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6,987
Location
Michigan
The best oil against heat would be a Ester based oil like Redline. The next would be a regular synthetic. Look for low Noack number. I would think a higher viscosity oil would help also as it would not seep past the guides and rings as easily. Once a oil gets to it's flash point you would have issues. The higher the flash point the better.
 
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3,756
Location
CA
For the third time, viscosity index improvers....... From Amsoil: "For example, viscosity index improvers are used to reduce the thinning effects caused by operation at elevated temperatures. They are the key components that allow for the production of multigrade oils. However, the long molecules in viscosity index improvers are subject to shearing in service, which reduces their ability to minimize fluid viscosity loss. Permanent shearing of viscosity index improvers can result in piston ring sticking due to deposit formation, increased oil consumption and accelerated equipment wear."
 
Messages
2,309
Location
Southwest Virginia
 Originally Posted By: fraso
Are there any Group II oils resistant to the high temperatures as found in piston ring grooves? If not, would any Group III oil be resistant?
Believe it or not, all else being equal Group I base oils are less prone to carboneous deposits in high temperature thin film environments than Groups II, III or IV. The higher aromatic content in Group I oils make them more polar and increase solvency, which can reduce deposits by dissolving polymeric oxidation by-products before going to carbon. See this thread from the past: http://www.bobistheoilguy.com/forums/ubbthreads.php?ubb=showflat&Main=63238&Number=803300#Post803300 Not all VI Improvers contribute to deposits - some such as high shear stable dispersant types can be quite clean. I believe the GM ban of 10W-40s was based more on political and marketing concerns than ring sticking. Tom NJ
 
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