dnewton3
Staff member
I've seen excellent results from HPLs PCEOs. (grp III, ANs, esters).
I'm also a fan of the ester based cleaners.
Reducing Likelihood of Sludge & Varnish ?
- Thread starter ChrisD46
- Start date
I'm also a fan of the ester based cleaners.
Here is good study from 1991 on sludge formation. From what I gathered from skimming though it, sludge formation is primarily driven by NOx and unburned fuel getting past the piston rings and contaminating the engine oil in the crankcase, which creates sludge precursors. More specifically it's NO2 (nitrite) from combustion and the olefin content in the gasoline. The sludge precursors then bind to insolubles in the oil to form sludge.
Operating an engine at low coolant and oil temperatures has a large effect on both the NO2 and fuel contamination of the oil. So, short trips encourage sludge formation, especially in cold weather. Using a block heater in cold weather should help prevent sludge formation. Oil life monitor algorithms are primarily based on the temperature of the engine, so they should provide a pretty good reference for estimating the risk of sludge formation.
The final step in sludge formation requires insolubles, such as soot, fuel, water, or wear metals to bind to the sludge precursors created by the NO2 and fuel. Limiting cold engine operation would help with water and fuel contamination, and good air and oil filtration would help with other insolubles.
The API grade of an oil also had a large effect on sludge formation, with an API SG oil outperforming an API SF by around a factor of 3. There have been large improvements in the sludge performance of oils between SG and the modern SN/SP oils. I believe Dexos gen3 requires sludge tests that are even more stringent than API SN/SP.
Operating an engine at low coolant and oil temperatures has a large effect on both the NO2 and fuel contamination of the oil. So, short trips encourage sludge formation, especially in cold weather. Using a block heater in cold weather should help prevent sludge formation. Oil life monitor algorithms are primarily based on the temperature of the engine, so they should provide a pretty good reference for estimating the risk of sludge formation.
The final step in sludge formation requires insolubles, such as soot, fuel, water, or wear metals to bind to the sludge precursors created by the NO2 and fuel. Limiting cold engine operation would help with water and fuel contamination, and good air and oil filtration would help with other insolubles.
The API grade of an oil also had a large effect on sludge formation, with an API SG oil outperforming an API SF by around a factor of 3. There have been large improvements in the sludge performance of oils between SG and the modern SN/SP oils. I believe Dexos gen3 requires sludge tests that are even more stringent than API SN/SP.
Kia recommends 5 thou or 6 mo whtever comes first + girlfriends 2018 DI 2.4L is the BLACKEST oil i ever seen in that time!!! shes does a lot of local + usually under 5 thou, BUT it dets dumped with a new OE filter!! my sludge prone as reported 2001 jetta went to 200 thou before trade running great, used Ams at first then Red after they went tight lipped on their oil formulations!! only just over 4 Qts like my 2001 TT that always got Red under my ownership. never seen the insides because there were NO issues!!
OVERKILL
$100 Site Donor 2021
Copying my post from @Graham Piccinini's thread:
I've posted on this subject many times and often get dismissive comments with respect to my position on varnish.
The reality is, as @wwillson alluded to with respect to the carbonaceous material in the ring lands, if you have varnish where you CAN see, you have a lot worse where you CAN'T.
That is, if the head(s) and valvetrain have managed to accumulate deposits, this means that the additive package of the oil has been overwhelmed. The dispersants and detergents are no longer able to do their job and so the materials they are tasked with holding in suspension through the mitigation of agglomeration and prevention of laying down, hit a saturation point and they plate-out. This is varnish.
Now, if you think it's bad seeing this showing up in these areas of moderate heat and reasonable flow, it's significantly worse in the ring pack where flow is extremely low and the conditions are the harshest.
Now, @aquariuscsm said that varnish is the precursor to sludge. That's only partially correct. Sludge and varnish are comprised of most of the same materials, but varnish doesn't necessarily lead to sludge and sludge doesn't typically lead to varnish. But you can have both happening in the same engine.
I've posted this chart before:
You can see that resins plating out leads to varnish. Varnish + carbon, water and solids can lead to sludge. But so can just those resins + carbon, water and solids. Varnish requires heat, sludge does not. If you have heat, you probably don't have water, which is why you end up with varnish instead of sludge.
These resins + soot can form silty deposits (often improperly referred to as sludge), or, they can form a thick dark varnish (heavy varnish) called lacquer.
It's easy to figure out what gets deposited in the ring land area, based on this data.
When liberated, it looks like this in your oil filter:
@wwilson has more examples.
I've posted on this subject many times and often get dismissive comments with respect to my position on varnish.
The reality is, as @wwillson alluded to with respect to the carbonaceous material in the ring lands, if you have varnish where you CAN see, you have a lot worse where you CAN'T.
That is, if the head(s) and valvetrain have managed to accumulate deposits, this means that the additive package of the oil has been overwhelmed. The dispersants and detergents are no longer able to do their job and so the materials they are tasked with holding in suspension through the mitigation of agglomeration and prevention of laying down, hit a saturation point and they plate-out. This is varnish.
Now, if you think it's bad seeing this showing up in these areas of moderate heat and reasonable flow, it's significantly worse in the ring pack where flow is extremely low and the conditions are the harshest.
Now, @aquariuscsm said that varnish is the precursor to sludge. That's only partially correct. Sludge and varnish are comprised of most of the same materials, but varnish doesn't necessarily lead to sludge and sludge doesn't typically lead to varnish. But you can have both happening in the same engine.
I've posted this chart before:
You can see that resins plating out leads to varnish. Varnish + carbon, water and solids can lead to sludge. But so can just those resins + carbon, water and solids. Varnish requires heat, sludge does not. If you have heat, you probably don't have water, which is why you end up with varnish instead of sludge.
These resins + soot can form silty deposits (often improperly referred to as sludge), or, they can form a thick dark varnish (heavy varnish) called lacquer.
It's easy to figure out what gets deposited in the ring land area, based on this data.
When liberated, it looks like this in your oil filter:
@wwilson has more examples.
Good post. It certainly does vary.
I would add that ASTM D6593 tests for sludge/varnish.
ASTM D6593
https://webstore.ansi.org/standards/astm/astmd659316a
1.1 This test method covers and is commonly referred to as the Sequence VG test,2 and it has been correlated with vehicles used in stop-and-go service prior to 1996, particularly with regard to sludge and varnish formation.3 It is one of the test methods required to evaluate oils intended to satisfy the API SL performance category.
I found it interesting how dewpoint impacts deposits and deposit chemistry. In Amsoil's controlled mechanical lab, they control the dewpoint when testing different oil chemistries and have found significant differences through controlling the dewpoint on certain chemistry types. This allows them to gain more insight into deposit formation.
See video at :55-2:50
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12 Months is too long in my opinion. Any short tripper with low miles will have moisture in the oil and cause sludge.
Also any oil in the engine for too many miles / months will get dirty/sludgy/clumpy and cause sludge, varnish, and dirty oil control rings / dirty piston rings. It was interesting to read the posts of many people who do extended OCI's. When they switched to an HPL Ester based oil, the photos of the cut open oil filters showed oil filters filled up with deposits. It would be interesting to understand how did their engine's get so dirty in the first place? Unfortunately UOA's don't capture how dirty/sludgy/clumpy the oil is when it drains out of the oil drain hole during an oil change.
My belief is that 4k/6 month (whichever comes first) OCI with any brand full synthetic oil gives high confidence of never having sludge/varnish/dirty oil control rings/dirty piston rings in any vehicle. That short OCI can also clean out a dirty engine with each successive oil change showing cleaner and cleaner oil being drained out.
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Take my Passat, it probably gets driven ~3K miles per year. I do a once/year change in that one. Not going to do it 2x at 1,500 miles...and that's even getting the oil change kits free ("free"...really for the cost of return shipping using FCP but it's less than $20). I make sure the car is driven regularly and gotten up to full temp - I consider driving an older car part of the caring of it - take it out for a hour stretch it out, WOT down the on ramp, etc. Annual changes are probably even overkill on that one, could probably just do every 2 years and I would wager it looks great inside/no sludge. I also use the LM flush product each change on that one (2 cans b/c 9 qts).
Thanks for sharing the photo, and providing the info on the clean engine with low mileage annual OCI's.
My vehicles are sludge prone, so my statements were more directed at my vehicles.
Glad to see your vehicles are not prone to sludge.
I see you are using Liqui Moly oils. Will you be switching over to HPL oil?
I've been doing the short OCI's in my vehicles for a long time, so next step is using HPL EC 30, and later HPL PCMO Group III + AN + Ester. I like the HPL PCMO Group III + AN + Esther, but don't like the PAO based oils, as the PAO could shrink engine seals. Do you have any concerns of engine oil screens / oil passaways / pcv valves getting plugged up during the cleaning with Ester based oils?
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I use the HPL 5W40 Euro in my Sportwagen. My reason is track use. In my W8 and Atlas I run LM...good oil with all the approvals that I get nearly free. I really am not concerned about issues running the PAO/Ester oils like HPL. I'm also not concerned about issues with cleaning and clogging things.
I believe you mean - more people should use the Severe Service OCI (i.e. 3,750 miles) versus extended OCI's of 7,500 miles or longer .
Not really. OVERKILL used M1 0w20 EP and the HPL liberated lots of gunk from his engine. So, I wouldn’t count on M1 keeping things clean
I think folks are referring the mystical properties of M1 0W40 vs. their other oils.
Some varnish is inevitable in the long-term. Sludge can be avoided easily, assuming the engine design isn't problematic. Getting the engine and oil nice & hot on a regular basis (at least once every 2 weeks) will be very helpful. Heating it up immediately before an oil drain is especially helpful to get rid of the nasty stuff.
i agree. i own a GDI engine with a lot of problems but sludge isn't one of them.and i do a 8000/year OCI, short trips unfortunately ,with a long trip once a week or every 2 weeks , 100 km go/back and using the oils you see, nothing special , ll04.
Is it bitog consensus that varnish is a harmless discoloration?
Serious question! I need to update my brain with the new data. lol
That's what I thought before joining bitog when I just used dino with 3K OCI. Thought varnish was just some discoloration like when you drop a fork in a campfire ... From then on, you use the fork for camping only and you can never invite more than 11 guests.
After joining bitog, I learned that varnish could cause issues with timing chain components, VVT, turbochargers, etc.
Should I erase this info?
I recently read the following on this Chevron Lubricant site. It's not talking about car engines but it was interesting. See the link below.
"Varnish buildup from oil degradation can cause serious problems in industrial turbines, hydraulic systems and compressors. Downtime, repair or replacement costs can run into the millions."
Chevron Lubricant - Varnish
Serious question! I need to update my brain with the new data. lol
That's what I thought before joining bitog when I just used dino with 3K OCI. Thought varnish was just some discoloration like when you drop a fork in a campfire ... From then on, you use the fork for camping only and you can never invite more than 11 guests.
After joining bitog, I learned that varnish could cause issues with timing chain components, VVT, turbochargers, etc.
Should I erase this info?
I recently read the following on this Chevron Lubricant site. It's not talking about car engines but it was interesting. See the link below.
"Varnish buildup from oil degradation can cause serious problems in industrial turbines, hydraulic systems and compressors. Downtime, repair or replacement costs can run into the millions."
Chevron Lubricant - Varnish
Looking back at some of the prior posts, even JAG found that M1 0w20 EP didn't have the solvency like Amsoil SS did. I think the prior M1 EP 0w20 was mostly PAO, but one of the weaknesses if you want to call it that was the lack of solvency of the HPL/Amsoil SS type oils. Likely had a splash of AN or whatever group V they went with for this grade.
I'd like to think this has changed with the recent Triple Action, which touts cleaning power in several of the PDS.
Yall know what is funny about this thread? the guys who know the most about keeping sludge and varnish away from their engine don't have any sludge or varnish in their engine because they border on being OCD about this subject whereas the people who have problems with sludge and varnish aren't on this forum nor do they actually care 
.
.You're right, in a sense. The people who have problems with sludge and varnish don't care about it... until they have a breakdown or other serious problem and are forced to pay for repair or replacement of the vehicle, plus vehicle down-time and other inconveniences. This unpleasant experience is how some people learn that maintenance is easier and cheaper than repair. But not all people who have a sludge-related breakdown will learn the maintenance lesson -- these are the people who truly do not care.Yall know what is funny about this thread? the guys who know the most about keeping sludge and varnish away from their engine don't have any sludge or varnish in their engine because they border on being OCD about this subject whereas the people who have problems with sludge and varnish aren't on this forum nor do they actually care
This is a theory I have, but unproven. Could anyone add insight into this.
Would you ever get sludge or varnish if you did 4k mile / 6 month oil change interval (whichever comes first) with a full synthetic 5W-30 oil (any brand) since the car was brand new, and after that OCI strategy lets say your car now has 200k miles on it? Assume that you have an engine design that is prone to sludge and varnish. Assume you do a mixture of city/highway driving with some short trips too.
The theory is that if the oil isn't in the engine long enough, the extreme heat of certain parts of the engine won't cause sludge/varnish
as the oil will be drained out during an oil change before the sludge/varnish forms from it.
Would you ever get sludge or varnish if you did 4k mile / 6 month oil change interval (whichever comes first) with a full synthetic 5W-30 oil (any brand) since the car was brand new, and after that OCI strategy lets say your car now has 200k miles on it? Assume that you have an engine design that is prone to sludge and varnish. Assume you do a mixture of city/highway driving with some short trips too.
The theory is that if the oil isn't in the engine long enough, the extreme heat of certain parts of the engine won't cause sludge/varnish
as the oil will be drained out during an oil change before the sludge/varnish forms from it.
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I know I am right. The people discussing the contents of motor oil are not reaching the people with the sludge problem.. and they never will.
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