Oil consumption - reduced by using a thinner grade

[virginoil]

Hi

I did a search on oil consumption and its variable and came across an interesting point by Pablo where he said than his vehicle drank 10w40 but didn't consume any when using 0w30.

Are there others that can atest this to type of engine oil behaviour. What was the oil grade causing the consumption and what oil grade help reduce the consumption.

I am not after an Auto-RX, double clean and rinse process response, I know this is a well respected product used for this.

 

[JAG]

Starting at ~60K miles on my VW GTI 1.8T engine, these oils were consumed:
Gold GC 0W-30, Lubromoly 0W-40, Lubromoly 5W-40, Syntec 5W-40, Mobil 1 0W-40

Amsoil ACD SAE 30/10W-30 is being used after the above oils and has no percievable oil consumption. This oil was first introduced to the engine when it had ~95K miles on it.

Oil fling-off from the rings into the CC is the major cause of "healthy" engine oil consumption according to one study. So reducing that will do the most to reduce it.

 

[RI_RS4]

JAG, there is one thing to keep in mind. The only way we have to measure oil consumption is by reading the dipstick. Unfortunately, in engines that fuel dilute, it can happen that oil burns off and is replaced by fuel. That fuel then burns off, leaving behind non-volatile "stuff". In these engines, even though a significant amount of oil has been burned, it does not appear so, since the level is compensated for by fuel and fuel byproducts.

I've also seen fuel diluting engines where oil consumption starts out low, then accelerates when the oil reaches some fuel dilution threshold, or oil degradation threshold.

 

[Audi Junkie]

^^^food for thought.

 

[bmwtechguy]

This is an interesting and unexpected result to read. The only thing I can think that all the oils that were consumed had some quantity of VII, but I've heard that the ACD has none. Better ring seal somehow? Any ideas from others?

 

[JAG]

My best guess in my case is better ring seal.

 

[RI_RS4]

Originally Posted By: JAG
My best guess in my case is better ring seal.


JAG, you are probably correct. That and lower volatility.

 

[ericthepig]

On the issue of fuel dilution convoluting your consumption readings - the oil level should be topped off and then chked after long hiway trips - this keeps the error at a min.

Meanwhile, I went to Pennzoil Platinum 5w20 in my 152k Sienna engine - the consumption has definitely not increased and I would say has decreased compared to 30 and 40 grades before it.

Also, this engine has ALWAYs created a very bad smell in the oil after just a hundred miles or so of an OC. A fuel/combustion product gunk smell - very strong (even after long HW trips). W/ the 5w20 there is almost no discernable gunk smell after a recent HW trip (2+k on the oil). VERY signficant difference! I can't remember the last time the oil in this engine smelled like oil - but now it does. (??)

 

[ConfederateTyrant]

There was a post on here in the past, that explained how thinner oils are more capable of creating a better ring seal because it can work it's way in there.

 

[demarpaint]

Originally Posted By: JAG
Starting at ~60K miles on my VW GTI 1.8T engine, these oils were consumed:
Gold GC 0W-30, Lubromoly 0W-40, Lubromoly 5W-40, Syntec 5W-40, Mobil 1 0W-40

Amsoil ACD SAE 30/10W-30 is being used after the above oils and has no percievable oil consumption. This oil was first introduced to the engine when it had ~95K miles on it.

Oil fling-off from the rings into the CC is the major cause of "healthy" engine oil consumption according to one study. So reducing that will do the most to reduce it.



Could it be that the oil being consumed was being consumed while the engine was cold, warming to 100*C which is when the oil is protecting best and in grade? Each of the oils mentioned were 0W-xx or 5W-xx, when switching to 10w30 the oil is thicker when cold making a better seal until the engine reaches operating temps?

JMO,
Frank D

 

[JohnBrowning]

Yes we hqave seen this behavior more then once on this site where thicker oils did not control the oil cunsuption as well as thinner oils. This is not though the norm it is rather a case of exceptions. In some case's Ow30 and 0W20 oils have reduced oil consuption in some applications! In most applications though it is just the opposite and the thicker oils reduce consumption more then anything short of fixinng the problem. I have best luck useing SAE 30, 5W40's and 15W40 to control oil consuption in peoples vechiles. Now my cars do not car what I put in them from 0W30 to 15W50 they do not consume any oil between oil changes tha can be descerned ont he dipstick with the exception of when I put in an ester based oil after running GII,GIII and PAO based oils then I always get a 1/4 of quart of oil consumption per 1500 miles for the first run of ester based oils .If I ru another ester based oil right after that I do not get any consumption at all. It must be ruing cleaning going on.

 

[Gary Allan]

Originally Posted By: ConfederateTyrant
There was a post on here in the past, that explained how thinner oils are more capable of creating a better ring seal because it can work it's way in there.


Yes. The fine Dr. Haas has provided authoritative sources stating that thinner oils migrate to the ring area better than heavier oils.

 

[virginoil]

Thanks for your responses.

I am currently using 10w30 Fuchs Group 3 oil in 1995/6 Buick V6 3800 L36 engine
100 deg Cst 10.9
40deg Cst 71
Pour Pt -39 deg C.
HTHS 3.5 Cst

Is there are benefit going thinner in an attempt to futher reduce oil consumption. Current usage about 1 litre in 3000km. with 215 000km on the clock.

Has has synthetic 90% of its life inculding 2 arx CLEANOUTS, HAS HAD THE SAME CONUMPTION FROM 40000KM with Mobil 1 5w50, Fuchs 5w40, Shell Helix 5w40 and Mobil 15w40.

Maybe a 0w30 ?

 

[Doug Hillary]

Hi,
Gary - Yes there is some research via Shell that confirms the speed of passage of a lubricant through the ring pack is viscosity related. There are quite obvious consequences of a slow passage such as oxidation and etc.

 

[ConfederateTyrant]

The Xw rating does not mean the oil is that thin at startup. Some of the 5w and 0w's are thicker than the 10w, depending on cold flow properties.

 

[nascarnation]

I don't know about reducing, but I can say in my old Saturn 1.9(130,000 miles) Pennzoil yellow 5W20 is probably no worse than GC 0W30 or Shell 5W40. Around half qt/ 2000 miles.

 

[widman]

There are SAE studies where single grade had much higher consumption than multigrades, Explained by the thicker oils not being able to drain back from the cylinders when the pistons come down to clean it off.