When does sludge really form?...only after the TBN drops below the safe level? Is it possible to have a good UOA (wear numbers/TBN) and still be forming sludge if there is not enough detergents in the oil, or will the UOA be able to detect this through the amount of particulates in the oil?
Criteria for sludge
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MolaKule
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In actuality, blowby gases and shear stresses in bearings are creating sludge all the time by creating hyperoxides and decomposed oil and additive molecules. These hyperoxides mix with soluble components of the oil to induce a chemical reaction called "polymerization." This is when "Useless Sludge Molecules" form (Patman's Favorite Roque Group). The agglomeration of all these molecules forms a brown to black tacky substance that will ahdere to engine parts and oil return passageways unless there is sufficient solvency to break them up.
Solvency may come in the form of the Magnesium/calcium dispersant-detergent packages, or as a cleaner such as Lube Control, Auto-RX, Neutra, etc. Motor Oil or supplemental solvents "depolymerize" the sludge, and attempt to break up sludge molecules, and then float them to the filter via the normal oil stream.
[ December 18, 2003, 07:30 PM: Message edited by: MolaKule ]
Solvency may come in the form of the Magnesium/calcium dispersant-detergent packages, or as a cleaner such as Lube Control, Auto-RX, Neutra, etc. Motor Oil or supplemental solvents "depolymerize" the sludge, and attempt to break up sludge molecules, and then float them to the filter via the normal oil stream.
[ December 18, 2003, 07:30 PM: Message edited by: MolaKule ]
I like to use a conservative lower limit of 4.0 on the TBN - w/ the ASTM D4739 test method - even though most labs use a cutoff of 2.0. This helps insure the engine stays extremely clean, regardless of the drain interval. It also reduces the chances of corrosive wear and rust in cold weather.
Blackstone, AVLube and Oil Analyzers are all using the ASTM D4739 protocol now, so that limit of 4.0 can be universally applied...
Blackstone, AVLube and Oil Analyzers are all using the ASTM D4739 protocol now, so that limit of 4.0 can be universally applied...
MolaKule
Staff member
The basicity of the magnesium/calcium add set the TBN, but the TBN is only an indicator of reserve acid fighting ability.
Not all sludge is acidic, but acids do contribute to the formation of sludge.
Not all sludge is acidic, but acids do contribute to the formation of sludge.
I'm not sure I can answer properly, but here goes.
Q:Is it possible to have a good UOA (wear numbers/TBN) and still be forming sludge if there is not enough detergents in the oil, or will the UOA be able to detect this through the amount of particulates in the oil?
A:
First off: Additives alone, do not determine the TBN. Oil does as well, and the balance IMO is what determines how well a package will HOLD in grade for the TBN, Visc, etc.
BUT I think Yes, I think TERRY with his secret methods, claims he can. He seems very credit worthy, so I would say most likely it would be possible but I don't know.
In general you can have sludge and still have good reports, but I think this may be more in SEVERE extended drains like I was doing 30K, 40K, 50K, 60K+... you can get a maximum saturation of GOO-OOP in the oil, and have FALL-out, and if you did what I did (not many filter changes, and only top-ups) maybe a certain fact. I don't recall the other ways sludge forms, but my tech people went over this with me long time ago and there are a couple.
Motor oils that have a natural high value from the oil will be able to 'work harder', High TBN's I think generally tend to help prevnt the 'LOADING' of gooo-ooop in most cases.
Most oils today are much better than yesterday, but they have to be 'cause the need is higher, and yes, most are still a little short, but that is not to say TBN is everything, it is only data to look at as with anything else.
There is more than one way to have a high TBN and to Maintain that TBN. Other things like VI will give the finished oil better resistance to Temp. change, thus less thinning and thickening and results are MINIMUM varnish, gum, sludge gooo-ooop.
Consider an oil fortified with HIGH detergency packages with a boosted oxidation stability= lower deposits and oil consumption= less Gooo-ooop= better performance.
Most oils USE-UP their TBN package FAST = no extended drains, I think this is because they use Cheaper oils (bases) and cheaper additives, and try to (here it comes) rely too heavily on their ADDITIVE package... BASE oil IS improtant - least for Dinos anyhow...
TBN by itself is only a little important, what you need to look at is how well it HOLDS it's level in a properly running engine... the longer it HOLDS, the BETTER the oil.
Engines are kinda like Blood and the body or the Body and food it is given...The Acid / Alkaline balance of the body fluids is possibly the biggest factor in HEALTH. Same with the motor oil, it wants to be Alkaline, not ACID...
I donno the proper PH of oil, but I think the blood is 7.4.
The body takes in food and breaks it down. The engine takes in food (oil, gas, air) and brakes it down. It IMHO, is determined mainly in the OIL, and somewhat in the fuel, air is going to be constant per se. How well the waste holds an ALKALINE nature is how WELL the engine will perform. It IMHO, depending on how well you remove waste (proper fuel/air ratio, blow-by etc.)
and so on, the life of the oil is either extended or reduced. This is why I feel, that there has to be a certain level where filters are changed, if nothing else than for the additional additive package. This is also why when aI have 'problems' I tend to change filters a lot more often, ie giving more medicine (strength and rest)to the components until the patient is healed. I do not want to run it to the max if I am keeping IT.
Sludge forms I think I'm saying it right, when all the floating goo-ooop clumps in chunks and starts to STICK someplace in the engine, ie a crack or hole or whatever. If the oil is not overloaded (extended) has enough additives, has a good base to begin with, it will resist this longer than other oils. My guess is this happens because the oil broke down and no longer has enough film strength, ie not enough cohesive or adhesive properties...
All things being similar, I think it would be the DISPERSANTS that surround the contamination and help keep it from forming GOOO-ooop!
IMO, the oils that keep the TOP end cleaner are these oils. They hold viscosity better... in fact I think maybe what a lot of people should start looking at is how well or how much longer Brand A or B will hold more GOOOOOO before moving to a specific viscosity (outa range or whatever). Ie how much additional weight can oil a or b hold compared to the respective oils available...
Anyhow, the question you should be working on IMO, is at what level TBN should you dump the oil based on 1. TBN only, and 2.based on 1-2-3 other levels raising an alert flag (and what levels are your alerts).
It seems as though your opinion is that if the WHOLE UOA is carefully analyzed, we "may" be able to ascertain whether an engine is forming sludge or staying clean, though not necessarily. I was asking from the aspect of how much faith we can put in the UOAs to extend our OCI with no risk of forming sludge--the answer seeming somewhat elusive.
I suppose the only thing that is somewhat sure is to pick a good oil and change it before its life is over--the obvious answer.
I suppose the only thing that is somewhat sure is to pick a good oil and change it before its life is over--the obvious answer.
Yup. You got it.
The faith you can put into it could be related to a Bank Deposit.
If you know you have enough to cover the check, you will not over-draw, unless someone wrote a bad check on YOUR account (fraud) ie. the bad check being a leak or other mechanical problem.
Again, Yes UOA's can help here too, as you can do what I do to spot these things several thousand miles before they show on the WEAR metals... look at the ratio of additives. I'm still attempting to figure it out but I have a system I work with to help me in MY special situation.
Sludge IMO is the LAST of your worrys, you can always do a flush. BUT you can never TAKE BACK extensive wear. Just by the fact that you are concerned about the possible sludging, is reason enough not to worry... when in doubt flush! Analysis of the flush should help toooooo
I had a problem awhile back about the LAB called me concerned about my comments.... they thought even though UOA's were okay, there could be sludge... anyway after a lond debate over months, I flushed the engine and sent that sample to them as per their outline, there was nothing nothing nothing... they were worried because of my extended drains and not any or very little filter changes.... anyhow they just could not believe I could do that to the oil and not have sludge, but then again no one ever did what I did before, because I did not care about sludge then because I was not keeping the car in my mind, but LIFE happens, and I'm still in it, and I wish I had not abused it, even though my parts and body will fall apart probably first.
Back to what I have always said but maybe not in so many words... YOU do NOT want to PUSH the OIL to it's limits... maybe once or twice, slowly, to test the limits, then cut back OCI in half or less... and stick to it... for those that don't put a lot of miles, maybe 60 or 70%, but don't push it! It is here, that you can determine when exactly where when things are normal, that the TBN starts to move SOUTH at a rapid clip... it is here that you can see how close to this clip does VISC get thick or thin, etc... it is here (UOA's) that you learn in your mind what your engine will do... and if you know something about UOA's or not, YOU will be able to SPOT the things OUTA the norm... This is where I gained anything, if anything at all... not in books, I know nothing, I just have a good IDEA what happens in My Engine, and when the ratios start to change, I know something is up... I don't always know what.
Molacule, does sludge form only when the oil is hot, or also when it's cold? Overall, is there more sludge forming during the summer months or winter? Is there a viscosity relationship to sludge formation with respect to range and thicker vs. thinner oils?
How about sludge forms when an oil is run too long or too hot and the additives don't work as they should .
MolaKule
Staff member
Oxidation and moisture start sludge formation. I would have to say that sludge forms quicker in cold weather, since condensation is greater. All other things being equal, moisture is evaporated quicker in hot weather.
On the other end, running oil too hot will also cause sludge through high temperature oxidation and the volatization or cooking off of lighter oil fractions. Obviously, excessive blowby and nonfunctioning PCV systems can also contribute to sludge formation.
Black death, or excessive sludge formation in the past, was caused by poor Viscosity Index Improvers shearing and breaking down.
The last part of the question is more problematical, since a large measure depends on oil base type.
A light viscosity petroleum oil should form sludge quicker than a high viscosity petroleum oil, since the lighter fractions would boil off much quicker.
I would have to say that a low viscosity full synthetic would produce less sludge than a high viscosity petroleum oil, due to the better stability of the base stock.
[ December 22, 2003, 11:49 PM: Message edited by: MolaKule ]
You have said 2.0 in the past. What's up?
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