Strange colored valvetrain and gunk
Joined: Jul 2013
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Yep that there is sludge and varnish. The only real way to get rid of that is to do more frequent oil changes. Little by little the detergents in the oil will start breaking that crud down. It can happen with any oil synthetic or dino, if you leave the oil in there more than it's supposed to, this starts to happen.
This was taken at 144,2xx miles, car has had 5k mile OCI with Castrol Edge 10w-30 for most of it's life.
PS, Castrol Edge is not a true synthetic in the exact sense of the word, it's based on group 3 base stocks. So it's more like highly refined dino oil.
This was taken at 144,2xx miles, car has had 5k mile OCI with Castrol Edge 10w-30 for most of it's life.
PS, Castrol Edge is not a true synthetic in the exact sense of the word, it's based on group 3 base stocks. So it's more like highly refined dino oil.
Thread Starter
Joined: Sep 2011
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From: Fremont, CA
Wasn't sure. Recently bought the car.
I agree. That orange/brown stain is called "varnish". I found that same (although a bit more brown than orange, without the pieces of gunk) varnish in my MDX after a number of years using dino oils. I switched to synthetic to stop it and try to remove some of it. Here is a shot of my S at 50K miles using Mobil 1. 
Here is a copy of an article by the American Society of Mechanical Engineers:AbstractVarnish formation, generated in a spark-ignited engine operating under various modes of speed, temperature, compression ratio, spark-advance, and air-fuel ratios, was investigated to establish the interrelationship between fuels, lubricants, additives, and engine operating conditions with respect to their effect and contribution to varnish deposition. The varnish precursors were identified to be primarily fuel aromatic compound. A series of engine tests was then conducted with blends of fuel aromatics and alkylate to determine their varnishing proclivities. Thus it was established that the varnishing characteristics of fuels are dependent not only on the total aromatics but even more so on the individual compounds. It was also determined that finished lubricants act as varnish inhibitors and thus determine to a high degree the engine varnish formation. On the other hand, of all engine variables, only the compression ratio and jacket temperature were found to be also of importance, although their total effect on varnish formation was smaller than that of the fuel or lubricant. Subsequently, the varnish deposits were removed from the engine parts, and a chemical analysis was made using modern instrumental techniques. The results showed the engine varnish composition is mostly alkane in character and contains condensed hydrocarbons, hydroxy-containing organic compounds, as well as ketones and nitro compounds. In addition, it was established that lead salts are also part of varnish but are not a prerequisite to varnish formation. Knowing the chemical composition of the varnish precursors, the composition of the varnish deposits, and the engine conditions under which these deposits were obtained, the chemical mechanism of varnish formation was defined by means of chemical equations. The final analysis of varnish formation is shown in the form of a computer-derived mathematical equation defining the relative importance of all variables affecting engine varnish deposition. Data are provided which show that piston varnish formation is a chemical process which occurs on the piston rubbing surfaces as the blowby travels from the combustion chamber to the engine sump.Copyright © 1969 by ASME
Thank you all for your responses as always 
Originally Posted by Billman250' timestamp='1453470725' post='23859909
That is conventional oil staining and buildup.If you use synthetic, you will never accumulate the slightest trace of anything.
Here is a copy of an article by the American Society of Mechanical Engineers:AbstractVarnish formation, generated in a spark-ignited engine operating under various modes of speed, temperature, compression ratio, spark-advance, and air-fuel ratios, was investigated to establish the interrelationship between fuels, lubricants, additives, and engine operating conditions with respect to their effect and contribution to varnish deposition. The varnish precursors were identified to be primarily fuel aromatic compound. A series of engine tests was then conducted with blends of fuel aromatics and alkylate to determine their varnishing proclivities. Thus it was established that the varnishing characteristics of fuels are dependent not only on the total aromatics but even more so on the individual compounds. It was also determined that finished lubricants act as varnish inhibitors and thus determine to a high degree the engine varnish formation. On the other hand, of all engine variables, only the compression ratio and jacket temperature were found to be also of importance, although their total effect on varnish formation was smaller than that of the fuel or lubricant. Subsequently, the varnish deposits were removed from the engine parts, and a chemical analysis was made using modern instrumental techniques. The results showed the engine varnish composition is mostly alkane in character and contains condensed hydrocarbons, hydroxy-containing organic compounds, as well as ketones and nitro compounds. In addition, it was established that lead salts are also part of varnish but are not a prerequisite to varnish formation. Knowing the chemical composition of the varnish precursors, the composition of the varnish deposits, and the engine conditions under which these deposits were obtained, the chemical mechanism of varnish formation was defined by means of chemical equations. The final analysis of varnish formation is shown in the form of a computer-derived mathematical equation defining the relative importance of all variables affecting engine varnish deposition. Data are provided which show that piston varnish formation is a chemical process which occurs on the piston rubbing surfaces as the blowby travels from the combustion chamber to the engine sump.Copyright © 1969 by ASME
Joined: Aug 2012
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Originally Posted by Slowcrash_101
PS, Castrol Edge is not a true synthetic in the exact sense of the word, it's based on group 3 base stocks. So it's more like highly refined dino oil.
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That SAE report on varnish formation implies that in order to get such deposits like seen in the photos of stained S engine, its not just old oil from long oci, but contaminated oil, from combustion gases.
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
Sent from my SM-G920P using IB AutoGroup
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
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From: Ontario Canada
That SAE report on varnish formation implies that in order to get such deposits like seen in the photos of stained S engine, its not just old oil from long oci, but contaminated oil, from combustion gases.
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
Sent from my SM-G920P using IB AutoGroup
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
Sent from my SM-G920P using IB AutoGroup
My car's engine had some light varnish on it when I bought the car, the previous owner ran Castrol Syntec religiously. It all cleared up after I started running Amsoil and Redline oils and completely disappeared. I've also found that Mobil1 keeps engines pretty spotless, much like the picture shown by Cosmomiller which is quite impressive in terms of cleanliness.
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Originally Posted by Car Analogy' timestamp='1453555390' post='23860707
That SAE report on varnish formation implies that in order to get such deposits like seen in the photos of stained S engine, its not just old oil from long oci, but contaminated oil, from combustion gases.
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
Sent from my SM-G920P using IB AutoGroup
The report says the varnish is a result of compounds found in fuels. That means this only occurs if oil has been contaminated from fuel (such as from blowby).
So leaving contaminated oil in the engine causes this. This would occur if you just stored the car with dirty oil. So change oil BEFORE winter storage if you were going to change it anyway in spring.
Sent from my SM-G920P using IB AutoGroup
My car's engine had some light varnish on it when I bought the car, the previous owner ran Castrol Syntec religiously. It all cleared up after I started running Amsoil and Redline oils and completely disappeared. I've also found that Mobil1 keeps engines pretty spotless, much like the picture shown by Cosmomiller which is quite impressive in terms of cleanliness.