Black Oil, Due To EGR system?

[Henro]

I was wondering why generally diesel engine oil turns black very quickly after an oil change.

But sometimes I see a post stating that the poster's diesel oil is clear, or pretty clear, after 50 hours or more of operation.

Planned on asking the "why" question, but reading another thread, I think the answer was offered.

Guessing that those who have non-black diesel oil may have tractors that also have poorly functioning EGR systems.

Could there be another reason?

 

[Captain13]

Black oil is normal for a diesel. Good oil picks up the soot/carbon and suspends it in the oil. Long idle time periods will create more soot and cause the oil to go dark sooner. Also, when the oils is changed, all of it doesn’t drain out. there is residual “dirty oil” in the ports valve covers, etc that gets blended in to the fresh oil. It doesn’t take much to turn the oil dark. So, don’t worry about it too much. It’s normal.

 

[85Hokie]

What Captain said.......

Oil in itself is a simplistically complicated substance. Hot or cold - it does it's job, and even after many hours still tries to catch all the bad stuff as it flows continually protecting the moving parts!

 

[Roadworthy]

Interesting question. My oil stayed virtually clear through the first fifty hours of tractor use. After the first oil change it is starting to get noticeably darker. Perhaps my Shell synthetic oil has more detergent or dirt trapping capability than the original oil? My last tractor's oil always got black shortly after changing it. I thought all diesel tractors did that. Perhaps my new Kubota has better rings?

 

[Henro]

What Captain said.......

Oil in itself is a simplistically complicated substance. Hot or cold - it does it's job, and even after many hours still tries to catch all the bad stuff as it flows continually protecting the moving parts!

I am not worried about it, and it has never been a problem in 20 years, but I like to understand why things happen sometimes, and this is one of those times...

Granted on a gas engine the oil will EVENTUALLY turn black, if you wait long enough. BUT with a diesel it is many time within a couple hours of use, or maybe slightly more, but not much.

Aside from soot carrying vapors being introduced to the crank case, is there another reason?

 

[Henro]

Interesting question. My oil stayed virtually clear through the first fifty hours of tractor use. After the first oil change it is starting to get noticeably darker. Perhaps my Shell synthetic oil has more detergent or dirt trapping capability than the original oil? My last tractor's oil always got black shortly after changing it. I thought all diesel tractors did that. Perhaps my new Kubota has better rings?

That is my question, I suppose. Seems like the two paths for getting the soot into the crankcase is past the rings, or via the EGR tubing...

Just seems like the EGR route would be the most likely, and someone who was not experiencing black oil might have a blocked EGR system.

My gut tells me it is the EGR path, after reading someone else's suggestion regarding that in another thread.

Perhaps as a test I should disable my EGR tubing, and open it to the atmosphere and see what happens. Older tractor without any high tech stuff on it, so I bet I could if I wanted to...but laziness will prevent me I fear...LOL

 

[Fordtech86]

That is my question, I suppose. Seems like the two paths for getting the soot into the crankcase is past the rings, or via the EGR tubing...

Just seems like the EGR route would be the most likely, and someone who was not experiencing black oil might have a blocked EGR system.

My gut tells me it is the EGR path, after reading someone else's suggestion regarding that in another thread.

Perhaps as a test I should disable my EGR tubing, and open it to the atmosphere and see what happens. Older tractor without any high tech stuff on it, so I bet I could if I wanted to...but laziness will prevent me I fear...LOL

I think you are confusing EGR system with the crankcase vent

 

[Dieseldonato]

Your really reading too much into it. Diesels burn very different from gas engines. They have been turning oil black since their inception. Egr systems shouldn't really have that big of an effect if the engine is being run properly with an effective load on it. The clean oil guys regardless of emissions tech or not, are typically the guys that do low hour oil changes on new or lightly used engines. Newer engines also have better tolerances then old engines. Thus negating some of the blow by that a well worn in engine has. Eventually they will all turn the oil black. It's really nothing to worry about.

 

[Henro]

I think you are confusing EGR system with the crankcase vent

You are almost certainly correct. I will have to investigate more...but I remember that there is a route for oil to travel from the crankcase into the cylinders, if you tip your tractor on its side, and I though that route was via the EGR path...

BUT I think you are right! So HOW do the vapors get into the crank case to darken the oil? I guess I need to study things further...more confused now than when I posted this thread!

Bottom line, I guess, is, is there a way for combustion gasses to get into the crankcase other than past the piston rings? If not, the answer is apparent.

I think I actually was referring to the PCV route, and got my terms mixed up. BUT not sure how exhaust gasses would get into the PCV system...

So the answer is likely that some get lucky and have a great piston ring seal, and those lucky people show less darkening of their oil over time...

Is this a reasonable conclusion?

 

[Fordtech86]

I think you will be looking for a long time to find an EGR tube on your tractors no matter what side you tip it on

 

[Henro]

Your really reading too much into it. Diesels burn very different from gas engines. They have been turning oil black since their inception. Egr systems shouldn't really have that big of an effect if the engine is being run properly with an effective load on it. The clean oil guys regardless of emissions tech or not, are typically the guys that do low hour oil changes on new or lightly used engines. Newer engines also have better tolerances then old engines. Thus negating some of the blow by that a well worn in engine has. Eventually they will all turn the oil black. It's really nothing to worry about.

Not worrying at all. Just trying to understand.

As I said in a post above (or recently, not sure of its position in relationship to this reply), it now looks like the ONLY path for combustion gasses to get into the crankcase is past the piston rings...is this correct?

Simple question, and maybe a simple answer...aside from my poor questioning ability...

 

[Dieseldonato]

You are almost certainly correct. I will have to investigate more...but I remember that there is a route for oil to travel from the crankcase into the cylinders, if you tip your tractor on its side, and I though that route was via the EGR path...

BUT I think you are right! So HOW do the vapors get into the crank case to darken the oil? I guess I need to study things further...more confused now than when I posted this thread!

Bottom line, I guess, is, is there a way for combustion gasses to get into the crankcase other than past the piston rings? If not, the answer is apparent.

I think I actually was referring to the PCV route, and got my terms mixed up. BUT not sure how exhaust gasses would get into the PCV system...

So the answer is likely that some get lucky and have a great piston ring seal, and those lucky people show less darkening of their oil over time...

Is this a reasonable conclusion?

Most the guys that have posted to "clear" Oil have low hour machines and change oil more often then needed. They will eventually see black oil at some point. It's pretty much unavoidable.
The crankcase ventilation system only puts a small amount of oil into the intake air stream. For years this was just vented to atmosphere. It really shouldn't be adding to the oil getting any blacker.

 

[Dieseldonato]

Not worrying at all. Just trying to understand.

As I said in a post above (or recently, not sure of its position in relationship to this reply), it now looks like the ONLY path for combustion gasses to get into the crankcase is past the piston rings...is this correct?

Simple question, and maybe a simple answer...aside from my poor questioning ability...

Yes that is correct. Past the rings.

 

[Henro]

I think you will be looking for a long time to find an EGR tube on your tractors no matter what side you tip it on

That is why I corrected myself and changed to PCV from EGR...my bad...I admit it...guilty as charged!

 

[torch]

Also, when the oils is changed, all of it doesn’t drain out. there is residual “dirty oil” in the ports valve covers, etc that gets blended in to the fresh oil. It doesn’t take much to turn the oil dark.

This is a much bigger factor than many realize. After a standard oil/filter change, the new oil will be substantially darkened after an hour. But if all the old oil is flushed out by changing it twice, it will take 10 or 20 times as long for the final fill to darken.

 

[Henro]

This is a much bigger factor than many realize. After a standard oil/filter change, the new oil will be substantially darkened after an hour. But if all the old oil is flushed out by changing it twice, it will take 10 or 20 times as long for the final fill to darken.

So is the conclusion is that black oil's root cause is blow by past the piston rings?

Essentially that stuff accumulates in the engine as the result, and that accumulated black stuff does not all drain out during an oil change...therefore, black oil is the result, soon after new oil is put in?

I guess so...makes sense...any consensus on this point here?

 

[Dieseldonato]

Yep pretty much. It's just the nature of the beast.

 

[Dieseldonato]

This is a much bigger factor than many realize. After a standard oil/filter change, the new oil will be substantially darkened after an hour. But if all the old oil is flushed out by changing it twice, it will take 10 or 20 times as long for the final fill to darken.

Who on planet earth has the time or extra money to change oil twice for no good reason? Good grief if I did that to every diesel I own/owned I'd be out a 55 gal drum every time I had to change oil.

 

[GBJeffOH]

I was wondering why generally diesel engine oil turns black very quickly after an oil change.

But sometimes I see a post stating that the poster's diesel oil is clear, or pretty clear, after 50 hours or more of operation.

Planned on asking the "why" question, but reading another thread, I think the answer was offered.

Guessing that those who have non-black diesel oil may have tractors that also have poorly functioning EGR systems.

Could there be another reason?

On my L4060 with the DPF filter the oil stays a lot cleaner than my ZD1211 zero turn. I don't know why.

 

[torch]

Who on planet earth has the time or extra money to change oil twice for no good reason? Good grief if I did that to every diesel I own/owned I'd be out a 55 gal drum every time I had to change oil.

Oh I don't advocate it as a routine maintenance step. I've done it once or twice just out of curiosity.

Is curiosity a good reason? I've wasted good money on dumber things in the past. <lol>