Old, dirty oil is a better lubricant than new oil...

[ralan]

...says one of my co-workers(a mechanic) He claims the carbon that builds up in the oil over time becomes a superior lubricant. He said that the only reason it is neccessary to change the oil is because of worn out additive packs.

I agree with the part about worn out additives, but the carbon (soot) as a lubricant?

I have read here on BITOG about the advantages of by-pass filters and their use prolonging engine life. I told my friend this, and he had never heard of a by-pass filter. I believe Shannow, who posts here from down in Australia, uses them with great results in a commercial environment. Don't they filter out the carbon? This evidence seems to negate my friend's statement.

Any comments welcome!!

ralan

 

[Blue636]

Sounds like hogwash to me.

 

[ralan]

quote:

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Originally posted by Blue636:
Sounds like hogwash to me.

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Yes, I think so. During this conversation, another mechanic came up and agreed about the carbon. He said that he could tell when his car needs an oil change because the oil starts leaking out the drain plug! This, assumably because of the superior lubricity of the carbon causing the oil to slide past the seal.

I think it is all engine oil "folklore", but I thought it would be good to get the Board's opinion on this.

[ March 05, 2004, 06:44 AM: Message edited by: ralan ]

 

[moontan]

soot ,the main enemy of a diesel engine.

 

[ralan]

quote:

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Originally posted by moontan:
soot ,the main enemy of a diesel engine.

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Also, the main combustion byproduct that ends up in the oil in a diesel engine

I love diesels, wish I still had one.

 

[Pablo]

Did you remimd him that diamonds are pure carbon?

BS He's even sorta wrong about the additive "packs"....

More proof that mechanics are not tribologists and the average Joe can, with a little time, learn and know the correct lubes and applications for their own cars.

 

[therion]

quote:

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Originally posted by ralan:
...says one of my co-workers(a mechanic) He claims the carbon that builds up in the oil over time becomes a superior lubricant. He said that the only reason it is neccessary to change the oil is because of worn out additive packs.

I agree with the part about worn out additives, but the carbon (soot) as a lubricant?

I have read here on BITOG about the advantages of by-pass filters and their use prolonging engine life. I told my friend this, and he had never heard of a by-pass filter. I believe Shannow, who posts here from down in Australia, uses them with great results in a commercial environment. Don't they filter out the carbon? This evidence seems to negate my friend's statement.

Any comments welcome!!

ralan

---

The motor guard with a tp element can filter out particles down to 1-3 microns with 100% efficiency. Soot particles can be as smaller than that so they keep the oil looking black. Thats why people with bypass filters and diesels still have black oil even though the oil is "clean". These smaller soot particles aren't as damaging as the bigger ones. Nonetheless i disagree i think soot and carbon is the enemy and having a clean engine is the #1 goal for longevity.

 

[RF Overlord]

It's amazing how many otherwise reasonable people can have some of the screwiest ideas about oil...

"It worked for my grandpappy on his 1918 Hispano-Suiza V8, so that's good enough for my V10 F-350!"

 

[Kestas]

If dirty oil is a superior lubricant, then why don't manufacturers make it that way? It's not as though there's a shortage of cheap soot in our contry.

 

[novadude]

Carbon is hard and abrasive. Not something you want in your oil.

 

[Bror Jace]

“More proof that mechanics are not tribologists …”

Bingo. As was pointed out, diamonds are a compressed form of carbon … one of the hardest substances known to man. They are a perfectly bad (abrasive) contaminant … probably one the best ingredients (along with silica) you could add to an engine oil to promote wear.

I was on nissanforums.com and someone stated their uncle was a Nissan mechanic and he said to leave the initial factory fill in for at least 4,000 miles. He said the initial metal flakes in the oil would help the rings seat better.

These kinds of zany myths and nonsense folklore are all over the place. The ‘seasoning’ varies a little here ‘n there but they have essentially the same sour taste.

Oil wants to seep/leak out of everything it is put into. The longer it is left in a container, the more likely it is to begin to succeed in escaping. Carbon content has nothing to do with it.

--- Bror Jace

 

[labman]

Carbon comes in 3 forms. Soot is amorphous, and not hard enough to be that abrasive. It is much easier on the balls in a ball mill* than the silica containing pigments. The problems it causes in an engine may be more with seals and gunking things up. Still, a little soot between a couple of pieces of metal may be better than nothing. Run too heavy of an oil, and maybe a little soot in the top end helps on cold starts.

Graphite is good stuff. It provides excellent extreme pressure protection that won't wash or boil off once you have a coat on metal. I use it a lot in places like locks. I am not sure there is a way of getting it coated on engine parts.

Diamond is very different from the other 2. It is hard and abrasive. It is also expensive. It has its uses.

*How do you stir soot into a thick resin to make black paint? You add them to a cylinder part full of inch steel balls and rotate it, letting the lumps of soot be crushed between the balls. Neither the balls or the cylinder last forever. When I worked for Rinshed Mason in the 60's, they had three 6' X 12' mills dedicated to making primer for GM. Two of them ran day and night. The third was out being relined.

 

[ralan]

Thanks everyone for the great replies

Now a question. Is coke (AKA burned oil residue) carbon?

 

[Bror Jace]

Thanks labman, for that primer on carbon. Someone mentioned graphite to me and I wasn't sure if it was purely carbon or some blend of other elements.

Just to throw this into the discussion, Arco made a graphite oil decades ago but it never caught on.

Question: Was it because the suspended solid carbon molecules provided no discernable benefit ... or people couldn't get used to the idea of pouring new, blackened oil into their cars?

--- Bror Jace

 

[heyjay]

quote:

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Originally posted by Dr. T:
I think the thought is that as an oil ages or is used, it will thicken because the thinner more volatile components are burning off. Does this make it a better lubricant than when new? No, but maybe as the consumption decreases, someone might think that the oil 'got better'.

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Exactly.

So why not use a proper heavier, less volitile oil from the start?

FWIW: our "Starburst" oils pass with flying colors if 275% thickening occurs in the test. Over 30% of the oil is allowed to boil off, and the test technician is allowed to add 6.5 litres of makeup oil during the test.

Contrast that to most ACEA A3/A5 and especially B4-02 oils: max thickening 50%, max volitility 20%, and the test technician may NOT add make-up oil during the test.

I once had a mechanic tell me the best thing to do was NEVER change the oil, just keep adding. It was "cheaper."

Sad thing is, I'm sure some well-meaning but uninformed folks believed that crackpot.

Jerry

 

[heyjay]

quote:

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Originally posted by labman:
Carbon comes in 3 forms. Soot is amorphous, and not hard enough to be that abrasive. It is much easier on the balls in a ball mill* than the silica containing pigments. The problems it causes in an engine may be more with seals and gunking things up. Still, a little soot between a couple of pieces of metal may be better than nothing. Run too heavy of an oil, and maybe a little soot in the top end helps on cold starts.

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Sorry, I run HD equipment and must disagree with your take on soot. For a motor, soot is about the worst thing you can have.

I'll quote from a new Esso XD-3 Extra product data sheet:

"Soot can cause wear of diesel engine roller-follower bushings and cross-over linkages ... low emission on-highway engines tend to put more stress on the oil by adding increased levels of soot. The oil needs to keep this soot dispersed to minimize its abrasiveness and neutralize the acidic material. Esso XD-3 Extra has a carefully balanced dispersant inhibitor package that controls soot-induced viscosity increase."

In many cases, soot acts like a slurry and completely wears out a motor.

Jerry

 

[MolaKule]

That's as bad as some people claiming that with a new oil, an engine shows higher wear. What they don't realize is the new engine oil with its fresh additive package is cleaning the crud left behind by the old oil.

quote:

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Question: Was it because the suspended solid carbon molecules provided no discernable benefit ... or people couldn't get used to the idea of pouring new, blackened oil into their cars?

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The graphite would reduce friction IF it could get to the surfaces and not be Washed off. However, the graphite introduced with the oil generally accelerates carbon mass accumulation because other pieces of carbon want to bond with it. Add to that the polymers in the sludge, and now, in addition, it wants to coagulate.

[ March 05, 2004, 03:49 PM: Message edited by: MolaKule ]

 

[Kestas]

Some of the posts here show a basic lack of understand the different forms of carbon found in nature and in man-made materials.

Diamond is pure carbon atoms arranged in a certain crystallographic pattern called zinc blende. The material is the hardest (and therefore the most abrasive) substance known to man.

Graphite is also carbon atoms, but arranged in a tall hexagonal close-packed crystallographic pattern and has one-tenth the density of diamond. This crystal pattern allows the atoms to slip over each other relatively easily, making it a superior solid lubricant. That's one of the benefits of cast iron in wear applications, it has graphite in the metal matrix.

Carbon can also be arranged in chains, sometimes called amorphous carbon. I'm not too familiar with this type of carbon, it has little value as an engineered material.

So the way I see it, carbon can be abrasive or a lubricant, or anything in between.

The only way to settle this argument is to extract a sample of carbon from used oil and run x-ray diffraction studies on the carbon. If the test shows the sample is mostly hexagonal close packed crystalline form, then it's a lubricant and helpful in the oil. If it shows an amorphous pattern, then it's either harmless or perhaps abrasive as some people have said.

 

[Bamaro]

If old oil was that good of a lubricant, all you would need to do is change the filter and top it off with a concentrated additive package.

 

[Kestas]

Bambaro, that's kinda what I said this morning.