Varnish with Synthetic Oil question

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I got interested in varnish for some reason and was reading some of the old threads referring to other thread ...
The following are from knowledgeable bitog members and were not disputed (at the time) and I am basically summarizing it here:

  • Varnish is the precursor to sludge. It is a sticky layer of precipitate that indicates that the contaminant carrying capacity of the lubricant was exceeded.
  • Saturated ("synthetic") oils have very low contaminant carrying capacity.
  • Group 3 and higher (4, pao, etc.) don't hold contaminants as well and have a limited capacity and need to be changed frequently.
  • In sequence VG varnish test, PAO barely met the minimum 9.0 merits and GTL only scored slightly higher.
  • Use Group II oils if you want to control varnish.
  • keep oci short even with full synthetic.

I'm trying to get to the bottom of it and have a few broad and related questions based on the above summary (facts?). I could have combined them into one question I have in mind but let's try this:

Q1:
If synthetic oils don't hold contaminants well, why are they known to be better at sludge control? Is the synthetic oil capability to carry/suspend sludge contaminants different or higher than it's capacity to contain varnish?

Q2:
Sounds like varnish and sludge are different contaminants and the capacity to "contain" them is also different but the "precursor" thing (refer to #1 above) is confusing me. Does precursor mean it's a sequence of events (varnish first then sludge) or are they independent processes or chemical reactions?

Q3:
Is it possible to have sludge without varnish? For example with group II oil?

Q4:
Related to Q3.
Sounds like with synthetic (or group 3+ or pao), if you have sludge then you should definitely have varnish since "synthetics" have a relatively lower capacity to contain varnish. No?
Have you seen an engine using syn (e.g. pao) that has sludge but no varnish?

btw as I mentioned, my summary was collected from posts by knowledgeable members (@ChemLabNL , @OVERKILL , @Gokhan , I think @Shannow and others) and hope I didn't take them out of context.

Thanks!
 
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It takes more time or more heat to oxidise the synthetic oils to the point of becoming varnish. Fully formulated oils contain detergents and anti-oxidants to keep this from happening, and dispersants to keep everything suspended in the oil until drain time. Synthetics will need more dispersants, but less anti-oxidants than a Group I oil.

Sonofjoe had some insights on this topic, but I doubt you can still find Group I oils in the USA.
 
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What make your motor happy makes your cat choke, start with a world class legacy engine that doesn't use oil and fill it with a full SAPS, HTHS, high Ca. additive lube and your golden.
 

OVERKILL

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- Sludge and varnish are formed through the same process, the difference is that sludge requires the presence of moisture:
SludgeVarnish.JPG


So yes, it's possible to have one without the other, though typically an engine with thick sludge also has significant varnish but you can also have crazy thick varnish with no sludge.

In terms of BASE OILS, the higher the group (with Group V excepted) the higher the purity the lower the solubility. So yes, PAO (Group IV) along with GTL and other Group III products like VISOM have inherently low solubility. That DOES NOT mean that the final products blended with these bases have low contaminant holding capacity or poor solubility however.

Oils of course are a BLEND of bases and additives. The additive package plays a critical role in suspending, and keeping in suspension the contaminants that will otherwise plate-out and leave deposits. These are the roles of your detergents and dispersants. This is why extended drain oils like M1 EP and AMSOIL have higher loadings of these products, since they have to do that job for much longer durations.

Typically, oils blended with PAO will also be blended with POE and/or AN's or some other group V base to increase solubility. Esters have excellent solubility, higher than what you are going to find in group II or II+ bases by a wide margin is my understanding, so it doesn't take a lot to add significant solubility to the base oil blend using this mechanism. The trade-off is of course that it is expensive.

So yes, focusing just on bases, a Group I will have much higher solubility than Group III, but it will also oxidize and produce the contaminants we are trying to contain much more rapidly, so it's a bit of a self-defeating exercise. At one point Shannow talked about how one could, using a Group I based straight grade, and EXTREMELY frequent changes, likely achieve some cleaning (oils are bad at cleaning) due to the high solubility of the base as long as the oil was swapped out frequently enough that it didn't succumb to its own degradation or become saturated with contaminants.
 
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Varnish is a precursor to the accumulation of sludge. Varnish inside newer engines is not good. Timing chain components, VVT operability, and turbochargers can all be negatively affected by varnish. Varnish wasn’t really a concern in older legacy engines so many people today still think varnish is nothing to worry about.
 
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I'm trying to get to the bottom of it and have a few broad and related questions based on the above summary (facts?). I could have combined them into one question I have in mind but let's try this:
Lets start with defining them because that seems to be the root of confusion that all things stem from.

Varnish by definition is the "residue" of a chemical reaction ( usually a combination of chemical reactions and heat) so you almost have to look at varnish in the specific stage of "creation" its in because each one has some unique differences on the chemical equilibrium.

In the beginning you have "soluble" varnish in that it can be removed and has not either deposited to a surface or fully contaminated the fluid.

Then it moves to the entire bulk of fluid is varnished and depositing.

Sludge is just the varnishing plus whatever it picks up along the way.

So, you can have one without the other.

Synthetics are more resistant to these things but eventually will fail themselves.

To address either ( or both) it must be addressed at the source- what is causing the reaction and why.

Realistically, no oil is immune or invulnerable to this and the speed/location of the formation is determined by the location and strength of the forces creating it.
 
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I have never seen a problem with varnish or sludge on a mechanically sound well designed properly maintained engine. That is why I ask, why the concern.? BITOG has pictures of properly maintained engines with the valve covers off that marvel the viewers.
 
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I have never seen a problem with varnish or sludge on a mechanically sound well designed properly maintained engine. That is why I ask, why the concern.?
From a mathematical perspective I agree and the risk is very low based on the criteria you mandated.

However, there are any number of conditions ( random and deliberate) which can tilt any scale and create conditions where varnish/sludge can form at an enhanced rate.

Like in another thread on washer fluid. I have driven to Ft McMurray twice ( this is me and not the usual airport rental). By every right my fluid should have frozen but it didn't. Don't know why.

I know that whatever latent heat and other factors didn't allow it to hit freeing or it would have.

Same with a machine ( engine or otherwise)- variations in tolerances, progressive wear, differences in loading, internal bore misalignment from external stresses and a whole lot more can create events where these things happen where the other 9 identical units sitting right beside it don't happen.

That's been my experience.
 
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From the 30 years in the field I have seen more sludge than I care to remember. Causes were mostly caused by a defect in emissions systems i.e. egr valve, oxygen sensor, pcv and very rarely from extended oil changes. I had the privilege of going to Texas for Toyota which we dove into the sludge problem at that time. Toyota blamed oil where technicians thought it was emissions related since they were cleaning out Emissions from exhaust.
 
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My 96 Volvo 960 has 134K miles on it. I pour a bottle of Auto-Rx in every 65K miles to get rid of the varnish. When I changed the oil two weeks ago after the initial cleaning phase the oil came out jet black with 4K miles of all highway driving. At 250 miles into the rinse phase the oil is already getting quite dirty. The car gets a once a year oil change with Mobil One 10W30 High Mileage.

The varnish on the rockers and cams didn't look that bad when I poured the Auto-Rx in last year. When I first Auto-Rx-ed it back in 2005, the varnish was really bad, afterward the rockers and cams looked as shiney as a brand new penny.
 

OilUzer

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Some of the old threads were alluding to or suggesting that synthetics are not as great as people might think and you still need frequent oci. Basically don't go overboard (oci wise) thinking it's all good. Varnish was one the examples and that synthetics are not good at it ... but what I may have missed is that maybe they were not talking about the "final" product.

Is it fair to say it's much more complex to formulate a real synthetic oil than it is to formulate a typical dino or blend? Basically much more that could go wrong ... granted there are certs and tests to catch the issues/problems. No?
 
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I have gotten rid of sludge with conventional oil and synthetic oil so I have no doubt both will work. When my grandma bought her 2015 Kia Soul used the oil looked like coffee I put Mobil 1 in and it was gone the next 2 changes. In my truck same thing but used Castrol conventional and got rid of the cheap jiffy lube oil that the previous owner had in there and it cleaned up the engine very nicely so I am confident both will clean sludge. Neither one that i know of had varnish in it.
 

OVERKILL

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Some of the old threads were alluding to or suggesting that synthetics are not as great as people might think and you still need frequent oci. Basically don't go overboard (oci wise) thinking it's all good. Varnish was one the examples and that synthetics are not good at it ... but what I may have missed is that maybe they were not talking about the "final" product.

Is it fair to say it's much more complex to formulate a real synthetic oil than it is to formulate a typical dino or blend? Basically much more that could go wrong ... granted there are certs and tests to catch the issues/problems. No?

The Euro certs with long life approvals test specifically for that, yes. And you'll notice it requires synthetics to meet the requirements of those certs. Yes, it's complicated, and I think it's a bit more delicate of a balancing act working with PAO, AN's and POE along with your heavy duty additive package to get a product that's sufficiently neutral with seals and gaskets while providing the necessary contaminant holding capacity to be suitable for greatly extended drain intervals. I get the impression that GTL, VISOM and other Group III's make the process a bit easier.

Of course these oils are expensive to blend relative to your standard Group I and II API oils that were the North American short drain standard around the time the LL oils started to appear on the scene. The modern iterations of these Euro lubes are likely still comparatively expensive to blend even with standards like Dexos now raising the bar and setting the new norm on this side of the pond. A40 isn't an easy test, neither are the Mercedes, BMW or VAG ones.
 

OilUzer

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Why the varnish concern? I like to find out why we have certain concerns?
OK, I'll give you some background info. Do you want the truth? Can you handle the truth? :)

Prior to bitog, I don't think I ever thought about engine varnish. Life was easier and I was buying Chevron Supreme at Costco and changing oil every 3-4K miles. I also avoided synthetic oils thinking it's a gimmick to milk the average consumer. lol NOT kidding you!

In general, I do a lot of research and study different things that interest me but engine oil was never on my radar maybe due to my success in having good running cars with 200+,300+,400K+ miles using regular cheap dinos like Pennzoil, Castrol GTX, Chevron Supreme, etc.

I never sold a car due to engine or transmission failure granted I only like and drove manual transmission. With no engine failures, oil was never a concern!

anyway, varnish is not a real concern but more of a curiosity that somehow came on my radar ... till something more interesting comes along. I also do believe and watch good Alien :alien: shows. lol

Edit:
If you want to connect more dots, I should blame Toyota. When I bought my 2016 v8 Tundra, I said what is this required 0W20 oil? Isn't it too thin? I was used to 30 and 40 grade and it led me to bitog since it was my first exposure to syn oil ... and it's a vvt-i engine.
 
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Synthetic CAN BE a gimmick. There's no advantage if someone is going to dump his oil every 3-4k like you did. But I'm sure the oil service places still try to sell synthetic to short changers for the extra profit...
 
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Synthetic CAN BE a gimmick. There's no advantage if someone is going to dump his oil every 3-4k like you did. But I'm sure the oil service places still try to sell synthetic to short changers for the extra profit...
Except for cold starts if it gets down to minus 20 or colder where you live. Also extra protection in the case of accidental overheating. Or maybe heavy towing if you're really working the engine hard. In those cases I'd be glad to use synthetic oil and "waste" it at 3-4k.
 
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down to minus 20 you don't need synthetic. There's 5w-xx synblends that go much lower comfortably. An engine that overheats is going to seize from parts expanding, or it doesn't if shut off in time.

For heavy towing or track use yes, you are better off with a synthetic. But it won't be wasted if dropped at 3-4k, it will be done.

Edit, I run a full sythetic (grpIII/PAO blend) for that reason aswell, with a slightly higher HTHS and slightly higher phosphorous content than an acea c2/c3 or Ilsac oil
 
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down to minus 20 you don't need synthetic. There's 5w-xx synblends that go much lower comfortably. An engine that overheats is going to seize from parts expanding, or it doesn't if shut off in time.

For heavy towing or track use yes, you are better off with a synthetic. But it won't be wasted if dropped at 3-4k, it will be done.

Edit, I run a full sythetic (grpIII/PAO blend) for that reason aswell, with a slightly higher HTHS and slightly higher phosphorous content than an acea c2/c3 or Ilsac oil
Maybe you're right about the temperature threshold but since we get that cold regularly for part of the winter I'll stick with full synthetic...and as for overheating...it doesn't always seize the engine, enough heat can cook the oil, so I don't quite understand your point there.
 
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