High Noack Oils and Dirty EGR Valves...

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If you have read any of my BITOG posts, you'll have heard me bang on about the problems of high Noack engine oils; particularly in the US.

My basic narrative is that in the right circumstances, hot blow-by gas will, over time, strip out the lightest components from a high Noack oil, route these through the PCV system, through the intake and into the cylinders. This leads to some oil loss and a visibly dirty intake manifold but these aren't the problems you really need to worry about. These heavy hydrocarbons do not burn well and partial combustion can leave behind very heavy, sticky deposits. This stuff can find it's way past the rings and leave deposits in the piston grooves. In extreme situations, this can cause an oil control ring to stick (unlike the top two rings, the OCR is not self-cleaning). Once this happens, your engine's oil consumption is likely skyrocket as oil gets pushed passed the top ring and directly into the cylinder.

The problem of oil front-end strip-out get worse as engines age and wear (more blow-by for a given fill of oil) or, if by virtue of living in a cold climate, you get fuel dilution (re-evaporating gasoline helps oil enter the vapour phase).

I am now wondering if there's another potential impact of high Noack oil in that over time, partially burnt oil can foul Exhaust Gas Recycling (EGR) valves? I've known about EGR for a long time as a means to reduce NOx on diesel engines. However I guess I wasn't so aware how EGR is being applied to gasoline engines as a means to improve fuel economy (by eliminating throttle body losses at load) and controlling knock (as an alternative to over fuelling). If I've understood things properly, EGR seems to feature heavily with the latest generation of TGDI engines.

What I find ironic is that EGR (especially cooled EGR), in lowering the peak combustion temperature, might make the problem of partial combustion of vapourised oil even worse, so you end up with MORE deposits with EGR and more sticky gunk, just waiting to gum up your EGR valve?

This only popped into my head because over here, the news is full of stories of VW fixing their emissions-cheating engines, only to have the fix followed by multiple EGR valve failures (apparently the fix requires the EGR valve to work so much harder).

Anyone else have any thoughts on this??
 
Joe,
a couple of data points while I process...

* EGR was early applied on petrol engines to reduce NOx on those carburettered at part throttle...usually had some strange pneumatic interlocks that wouldn't apply it until engine was at temperature (and usually locked out vacuum advance until top gear enabled as well).
* Recall Monash University in the '80s trying to replace a Camira engine with an OPEL 1.3, high boost turbo, and controlling using EGR, and the vacuum slide/guts of an S.U. carby to avoid throttling losses...worked OK, but when it didn't ... Bang, it destroyed pistons...we've come a long way with electronics.
* My ex Navara, with the ZD30 turbodiesel had two intake valves per cylinder, one high swirl, with EGR, the other for volume air flow, no EGR...a little butterfly closed the high volume ports, and a main butterfly partially choked the engine to get the EGR to flow (differential pressure)...the inlet manifold on those engines is incredibly wet with oil...the High swirl port was invariably black with carbon, or worse...no inlet valve deposits on the wet but clean port, deposits on the wet/dirty/egr port.
* AUDI had a patent (and I can't find it) that modified the chemistry of the oil to prevent (and remove) Intake Valve deposits. The inference was that it cleaned them, rather than (for example) lowering NOACK to reduce carry through.

This is what I mean on the ZD30 ports...not mine, I blew away the photos when I sold it.


Mine was a black paint like sheen, not the fluffy crusty stuff...Car spent most of it's life on synthetics (Castrol/Mobil 0W40), followed by 5W40s (Castrol and Mobil GrIIIs), then Edge 5W30 A3/B4 with a 20% edge 25W50 booster...just for reference.
 
I thought you were on the right track yesterday with your forensic analysis of the synthetic lubricants not burning in the combustion chamber, instead loading up on the top ring.
A back story:
A lubricant's resistance to oxidation in a 2-stroke engine is good for lubrication and helps pass TWC smoke limits.
Another application would be in piston aircraft engines.
The piston fit is very loose, and those engines consume a lot of oil without gumming up.
Typically piston aircraft engine oils are mono-grade with extremely high flash points.
That suggests low Noack and no separation of light and heavy ends.
EGR as you mentioned, cools ignition temperature.
It would be interesting the effect egr would have on an air cooled engine in escalating amount with different engine oils.

Edit, a few days back you mentioned that sulfur is stripped out of group II and II base stocks, but remain in group I
and act as a solvent. That could help eliminate the build up of ring zone deposits in high noack engine oil.
The best 0W40 synthetic might be the worst for ring zone deposits, proving your premonition correct.
 
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Shannow,

Interesting...

Regarding Diesel EGR, I'll bow to decades of real-life use which says EGR is a safe option regardless of what oil you use. All I would say is that as commercial HDDO's are concerned, 15W40 (for years, the commonest global HDDO grade) would by it's heavy nature have a low Noack. Also oils for European diesel passenger cars (eg 10W40 & 5W40) which meet ACEA specs also tend to have low Noacks. This is part due to the Noack spec being more restrictive (13% max as opposed to 15% max in the US) but mainly due to the high use of Group III in these grades (often to pass tests like the Peugeot TU3 in A3 or the VW TDi in B4).

When composing the post, I very much had the US in mind, where EGR on gasoline engines already seems normal (because big engines are more prone to throttle body losses???) and where TGDI is coming in at a rapid pace. To me, there seems to be a potential conflict between this and a nation wedded to making weird fuel economy orientated oils with as much use of light Group II as is conceivably possible. I might worry less if API/ILSAC were showing signs to tightening up the 15% max Noack spec when GF-6 comes in but I very much doubt the oil companies would ever support such a move.
 
EGR was on everything 70s and 80s. It, and the things that went around it typically contributed to 20% more fuel consumption, and a similar power loss. Cat-Cons gave another NOx control mechanism in the 80s, and a lot of Oz's petrol engines regained their power, could again hit 30MPG.

(I had a 1978 V-8 auto, that I got to 30MPG through mucking around. EGR at idle, with porting directing the exhaust gasses directly at the idle fuel ports on the Q-Jet carb. Full vacuum advance at idle. Thermostat to control coolant inlet temperatures rather than outlet. PCV fumes routed through a copper pipe wound around the exhaust manifolds and wrapped in insulating tape, and as a result of all the heat, had to use fuse wire in the transition fuel ports to get the idle screws to adjust enough...it was a finnicky POS to get running, but ran great on the highway...and 30MPG...had to pull the junk off to sell it but)

EGR on consumer diesels (in Oz) is a new Century thing...and it's very high rate compared to the back in the day petrol engines.

Re the Pug test...is my reading of your post correct that the NOACK specification was virtually superfluous when an actual engine test was specced ?
 
Originally Posted By: Shannow
EGR was on everything 70s and 80s. It, and the things that went around it typically contributed to 20% more fuel consumption, and a similar power loss. Cat-Cons gave another NOx control mechanism in the 80s, and a lot of Oz's petrol engines regained their power, could again hit 30MPG.

(I had a 1978 V-8 auto, that I got to 30MPG through mucking around. EGR at idle, with porting directing the exhaust gasses directly at the idle fuel ports on the Q-Jet carb. Full vacuum advance at idle. Thermostat to control coolant inlet temperatures rather than outlet. PCV fumes routed through a copper pipe wound around the exhaust manifolds and wrapped in insulating tape, and as a result of all the heat, had to use fuse wire in the transition fuel ports to get the idle screws to adjust enough...it was a finnicky POS to get running, but ran great on the highway...and 30MPG...had to pull the junk off to sell it but)

EGR on consumer diesels (in Oz) is a new Century thing...and it's very high rate compared to the back in the day petrol engines.

Re the Pug test...is my reading of your post correct that the NOACK specification was virtually superfluous when an actual engine test was specced ?



It's strange to think that there was once a time when petrol engined cars DIDN'T come fitted with a catalytic converter to zap nasty NOx! However I sort of remember that back in the seventies, I was less concerned about emissions and more concerned with windscreen wipers that fell off while driving along, sills that rusted through, driving on highly lethal £5 remold tyres, hand brake levers that detached themselves from the floor when you pulled too hard, gaping great holes in the front bulkhead which let water in when it was wet, the horrendous stink inside the car from sodden, mouldy carpets & leaking rear drum brake slave cylinders that made stopping in an emergency a 'brown trousers' moment. And you tell that to kids of today, and they don't believe you!

Yes, the TU5 did limit Noack to well below 13% especially on 10W40s. You could cheat the test with Shellvis VII but as it cost twice as much as OCP, it was always something of a pyrrhic victory. Likewise with the VW TDi, you could beat the test by adding more Ashless Dispersant or you could beat it my using more Group III in a semi-synthetic to reduce the level of VII. Often the latter approach made more sense when you took everything into consideration. If like me, you come from this 'low Noack' normality, the very high, close to 15%, Noacks you see in the US look very abnormal.
 
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re your first paragraph...my first cars were the Oz 6 cylinder version of the slope backed Vauxhaul Vivas...when I was 7, we moved states, in a Datsun 1000 station wagon...I still remember having the handbrake cable pulled up through the drain bung in the rear seat floor (remember cars having drain bungs ???), and my old man screaming at me to pull the cable or we'll all die...
 
SonofJoe, you recently trashed the Lubrizol Global Marketing Director on low-SAPS oils reducing valve deposits in GDI engines in actual field studies. I kept my mouth shut at that time. Then you post something incredibly outrageous as this?

Heavy carbon on EGR valve has nothing to do with oil, let alone 15% vs. 13% NOACK. It's caused by faulty fuel and/or emission systems. It's basically the excess HC in the exhaust caused by incomplete combustion.

I had that problem a while ago. I had to use a flat-blade screwdriver and brake cleaner to remove the rock-hard carbon from the EGR valve. I was using Delvac 15W-40 with 11.3% NOACK. I rebuilt the carburetor and replaced the broken EGR vacuum modulator and the problem has been gone for good, despite running "high-NOACK" TGMO 0W-20 SN.
 
Well given that the light end of the lubricating oils that Joe is talking about fall into the worse than bad (faulty) fuel ends (especially in petrol engines), were NEVER intended to be ingested as a fuel...how do you judge the idea as "outrageous" ???
 
Originally Posted By: Shannow
Well given that the light end of the lubricating oils that Joe is talking about fall into the worse than bad (faulty) fuel ends (especially in petrol engines), were NEVER intended to be ingested as a fuel...how do you judge the idea as "outrageous" ???

The argument is so faulty that I wouldn't know where to begin with. NOACK contributing to only a small fraction of the oil consumption? 13% vs. 15% not being too different in engineering sense? Me having actually experienced this with a 15W-40 with 11.3% NOACK? Me having personally repaired the carburetor and emissions then not having experienced it again with TGMO 0W-20 SN? As opposed to SonofJoe speculating theoretically from his armchair?
 
In NZ we didn't get EGR and cats until late in the piece - we wondered what those blanking plates on inlet and exhaust manifolds were for. Cats are only compulsory here after 2010, or at least you can't remove a cat from a car later than that.

We could be talking about different versions, but on the twin butterfly ZD30 as in Shannow's pic, the clean port does crankcase breather only, the dirty port is EGR, so it's not oil alone. Deposits are also much greater with common rail and EGR coolers, hard to know what is the common denominator as they go together. We get manifold and valve deposits, but EGR valves seldom give trouble with deposits...and they are pretty easy to clean or replace anyway.

This is a Mazda BT 50 to show how much these EGR diesels clog up...crankcase breather and EGR combined here. I think the square ports are the swirl ports. Oh no, I can see the butterfly in the round port...

 
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You mention 15W40 mineral oils and Euro 10W40 A3/B4 semi-synthetics as being fairly low in Noack.
What would their typical Noack values be ?

I haven't seen much data on them.

Thanks.
 
Originally Posted By: Silk
We could be talking about different versions, but on the twin butterfly ZD30 as in Shannow's pic, the clean port does crankcase breather only, the dirty port is EGR, so it's not oil alone.


Yep, butterfly port is oily, EGR port (although the EGR is introduced WAY closer to the head than that end of the port) is the bad one.
 
I should mention that I also had a high oil consumption problem due to bad valve-stem oil seals at that time, but I just can't see how it could be caused by oil. 15% instead of 13% NOACK causing heavy, hard carbon deposits? What is special about the number 13? Besides, I was using an 11.3% 15W-40 HDEO. I should also mention that my intake manifold was as clean as it could be despite the completely clogged EGR valve being directly attached to it. Gasoline is an excellent cleaner.

I don't operate a repair shop to report many cases but my neighbor told me that he had the same problem in his 2003 Maxima. He religiously uses Royal Purple 5W-30, which has 10.9% NOACK. It was pretty bad and the funny thing is that the mechanic cleaned it with the same flat-blade screwdriver/brake cleaner method I used but spent at least an hour. I guess common sense leads you to the same solution. Cause? Obviously not the oil but some faulty ignition or fuel-system part causing incomplete combustion.
 
Originally Posted By: Gokhan
I should also mention that my intake manifold was as clean as it could be despite the completely clogged EGR valve being directly attached to it. Gasoline is an excellent cleaner.


Gasoline never gets to the "Exhaust Gas Recirculation" Valve...this valve takes "Exhaust Gas" and reintroduces it to the inlet manifold, after the carb, and before the inlet valves.

You had high volumes of oil going out the exhaust, due to your own admission mechanical failure, which obviously went out the "Exhaust Gas" path, and some through the EGR...You fixed your mechanical issues and have not seen recurrence on a higher NOACK oil...
 
I meant the exhaust gas through the valve couldn't get the intake manifold dirty.

I think it was carburetion, not oil consumption. Oil burns fairly well to most part (excluding ashes etc.). Many cars consume oil. In any case no one having this problem will see an improvement with better NOACK as I explained. It either happens catastrophically or doesn't happen. 13% vs. 15% NOACK will have no effect even if it was (I don't think it was) oil. My neighbor had the same problem without oil consumption.
 
Originally Posted By: Shannow
re your first paragraph...my first cars were the Oz 6 cylinder version of the slope backed Vauxhaul Vivas...when I was 7, we moved states, in a Datsun 1000 station wagon...I still remember having the handbrake cable pulled up through the drain bung in the rear seat floor (remember cars having drain bungs ???), and my old man screaming at me to pull the cable or we'll all die...


Yeah, I had a Dad like that. No instruction could be conveyed to a child without it being barked out at 200 decibels and being steeped in such life-threatening menace that the only option was to obey; instantly!!

Funnily enough your brake cable story reminded me of my old Fiat Mirafiori that I foolishly bought in the early 80s. Everything on the car was held together with plastic screws and plastic clips. For ages, I couldn't get the heater to work properly. I'd move the slider over to hot and nothing much would happen. Then one day I got fed of freezing to death and started pulling the fascia apart. I then realised that the two plastic clips that were supposed to hold the heater cable sheathing had snapped off, so when I moved the slider, the entire cable moved but nothing else did! Maybe it was that made me deeply suspicious of things that look ok on the surface but are actually very wrong when you look a bit deeper...like EGR valves for example.
 
Originally Posted By: SR5
You mention 15W40 mineral oils and Euro 10W40 A3/B4 semi-synthetics as being fairly low in Noack.
What would their typical Noack values be ?

I haven't seen much data on them.

Thanks.



From what I recall OCP-based Group I 15W40s would fall out with a Noack of about 7.5% (less if made with Shellvis).

Semi-synthetic 10W40s are interesting. You typically might need 20% Group III just to meet 13% Noack but 40 to 50% might be needed to get an 'honest' TU5 A3 pass (not all passes were IMO honest but you just can't accuse people of cheating). That might drop the Noack down to say 10.5-ish. Factor in ACEA B4 and you might up the Group III even more.

One thing to bear in mind with 15W40s & 10W40s is you're chasing a 7000 max CCS with no silly ILSAC style fuel economy tests to complicate things. Having a higher CCS helps greatly on Noack.
 
Originally Posted By: SonofJoe
One thing to bear in mind with 15W40s & 10W40s is you're chasing a 7000 max CCS with no silly ILSAC style fuel economy tests to complicate things. Having a higher CCS helps greatly on Noack.


within the MRV and CCS, MRV being low shear rate "gravity falling to the pickup", and CCS being a high shear rate property, sort of akin to HTHS, but at high shear rate, Low temperature.

Again...polymer treat rate and BOV
 
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