Why is oil consumption so common?

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So how should a solution look like in a case where we get less than optimal seal between the rings and the liner and consequently huge consumption (that is within manufacturer's limit)?

Add honey-like VII additives to my oil that I fear will promote big end cavitation?

Use 10w60 (one of the manufacturer's recommended spec) that I fear will cause the same?

Live with it and use the cheapest brand I can get?

Re-route the PCV to the atmosphere in order to alleviate some of the blow by back pressure?

Continue to experiment until I find an oil my Bella will not drink?

My incline is toward latter of the five options. I believe there is an oil out there that will cure it.

What do you think?
 
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Originally Posted By: FZ1
Try some Mobil Super High Mileage oil.


Is it that much different to Maxlife? I have tried it for two OCI's. No joy. I really did think it would clean the rings but alas... The plumes keep on clouding behind us as I rev...
 
Originally Posted By: TFB1
There should never be large amount of pressure in the crankcase from blowby, any excess will be vented back into the air intake which is then pulled into the engine... Only if this portion of the system was plugged would there be a problem...
Originally Posted By: Alfa_Hadera
So how should a solution look like in a case where we get less than optimal seal between the rings and the liner and consequently huge consumption (that is within manufacturer's limit)?

Add honey-like VII additives to my oil that I fear will promote big end cavitation?

Use 10w60 (one of the manufacturer's recommended spec) that I fear will cause the same?

Live with it and use the cheapest brand I can get?

Re-route the PCV to the atmosphere in order to alleviate some of the blow by back pressure?

Continue to experiment until I find an oil my Bella will not drink?

My incline is toward latter of the five options. I believe there is an oil out there that will cure it.

What do you think?



I lean the same way
 
All of my 12 cars ran over 100k and all needed some oil between 6k-mile OCs...typically 1/2 qt...@100k the Kitacam has gone 5.5k on this, it's first syn OCI, and is just at the "L" mark with none added....we'll see how it "grows into" syn and how the oil lasts on the 2nd syn. OC...
 
Originally Posted By: Alfa_Hadera
Originally Posted By: FZ1
Try some Mobil Super High Mileage oil.


Is it that much different to Maxlife? I have tried it for two OCI's. No joy. I really did think it would clean the rings but alas... The plumes keep on clouding behind us as I rev...
Dunno. I never had clouds of smoke,just oil blackening and a drip with EP 5w-20. Went to Mobil Super High Mileage 5w30 and the oil is not blackening and the drip has,virtually,stopped. I think the density of the High Mileage oils is part of the reason the burning is reduced,but the Maxlife blend is slightly more dense than the MSHigh Mileage so it may not help,in your case. p.s. I do think the MSHigh Mileage 10w-40 is even more dense than the 5w30 I used.
 
There are so many people here saying that low tension compression rings are the cause of oil consumption. Compression rings are not responsible for controlling oil consumption. The oil control rings do that. Any talk of rings causing oil consumption need to focus on the oil control rings. Compression rings seal compression, oil control rings control oil.

This is why a compression and leakdown test will never tell you anything about oil consumption - the oil control rings do not seal compression and therefore can not cause low compression. If you have low compression, you've got bigger problems than oil consumption.
 
Originally Posted By: Scott_Tucker
There are so many people here saying that low tension compression rings are the cause of oil consumption. Compression rings are not responsible for controlling oil consumption. The oil control rings do that. Any talk of rings causing oil consumption need to focus on the oil control rings. Compression rings seal compression, oil control rings control oil.

This is why a compression and leakdown test will never tell you anything about oil consumption - the oil control rings do not seal compression and therefore can not cause low compression. If you have low compression, you've got bigger problems than oil consumption.


Not quite. If the compression rings are not seated properly, they will allow excessive blow by that will hit the oil control rings causing them to gum up, stick and not scrape the excess oil from cylinder walls. Some of that extra oil gets burned up, but some ends up coating the oil control and compression rings, further gumming them up with hard carbon deposits. It's a very slow process, but once started it feeds on itself and eventually may cause low compression.

That is why engines with properly seated compression rings do not burn oil as there is nothing there to start the process. Also, occasional heavy throttle applications and getting the engine into higher revs. helps as well.
 
It sounds like what you are saying is that an engine which has worn compression rings that are causing excessive blow-by will cause the oil control rings to carbon up and stick, thus becoming ineffective. This is certainly a fully feasible scenario and I have no doubt it happens. However, for compression rings to have excessive blow-by, you must by default have low compression. The engine having low compression will always trump oil consumption. Who cares how much oil your V8 engine consumes if it is only running on 6 cylinders due to low compression in a couple?

Now look at this scenario. I have an engine that runs well and consumes no oil. I do a compression test and all cylinder fall within a few pounds of 160 PSI - everything is normal. Now, I take the engine apart, remove the oil control rings only, and reassemble. I do the same compression test, yet now my compression numbers are 165 PSI across the board but the engine is now consuming a quart in 500 miles but otherwise runs OK. The increase in compression is caused by excessive oil improving the seal of the rings (just like on a wet compression test, but it won't jump up as much as if it had bad compression rings).

So what did this compression test tell you about the oil consumption problem? Nothing. As a matter of fact, according to most of the bad advice you hear on the internet your oil control rings are OK. In this case they are non-existent! Oil control rings have drain holes behind them that will never allow them to seal gas. You could also do a leakdown test and it would come out perfect.

Obviously, no one is going to remove their oil control rings but the exact same thing happens when the oil control rings stick due to carbon. It's like they are not even there. As matter of fact, most oil consumption problems I have dealt with have great compression, but stuck oil control rings. And this is from the observation of hundreds of engines. Engines are what I do professionally and I am one of the top in my field.

This whole compression and leakdown for oil consumption is probably my biggest pet peave when it comes to automotive forums. This misinformation has been spreading for years.
 
Our Uplander 3.5 uses about 1/2 quart every 3000 miles. My Accord 2.4 uses none over 3000 miles, not that I can tell anyway, still at the same spot on the dipstick.
 
I've had success doing piston soaks with marvel mystery oil. There are other good products that members here can recommend too. Basically you need something with a lot of detergents to help break down the deposits.

I just changed the oil in my 2.4L '12 Civic Si, and after 8000 mi the oil was only down about 1/2 a quart. I'm lucky because some people have been having oil consumption problems with this engine.
 
We don't get MMO here or any other type of dedicated additives that are for soaking - just the normal flushes like Liqui Moly's.

Are these bad for soaking? Can I be OK w Kerosene?
 
Originally Posted By: Alfa_Hadera
We don't get MMO here or any other type of dedicated additives that are for soaking - just the normal flushes like Liqui Moly's.

Are these bad for soaking? Can I be OK w Kerosene?



I see that you are in Israel. I guess no Chemtool B12 or Kreen either, right?

Flush fluid should work I guess. Not sure how well. Most of them are kerosene indeed.

Edit: according to this discussion, it should work fine: http://www.saabcentral.com/forums/archive/index.php/t-223411.html
 
Ok,

I take it back. I just checked and I have burnt 1/2 a quart at the 4,000 mile mark with 10w40 NextGen Maxlife, I had 1/2 a quart laying around and topped it off with the same type of oil. This isn't bad consumption on a 5.7 Vortec is it?
 
Originally Posted By: Nick1994
Ok,

I take it back. I just checked and I have burnt 1/2 a quart at the 4,000 mile mark with 10w40 NextGen Maxlife, I had 1/2 a quart laying around and topped it off with the same type of oil. This isn't bad consumption on a 5.7 Vortec is it?


A half quart at 4K mi isn't bad in ANY engine, though you'll no doubt get the sky is falling routine form all the OCD-ites here on BITOG...
 
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